// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_SET
#define _LIBCPP_SET

/*

    set synopsis

namespace std
{

template <class Key, class Compare = less<Key>,
          class Allocator = allocator<Key>>
class set
{
public:
    // types:
    typedef Key                                      key_type;
    typedef key_type                                 value_type;
    typedef Compare                                  key_compare;
    typedef key_compare                              value_compare;
    typedef Allocator                                allocator_type;
    typedef typename allocator_type::reference       reference;
    typedef typename allocator_type::const_reference const_reference;
    typedef typename allocator_type::size_type       size_type;
    typedef typename allocator_type::difference_type difference_type;
    typedef typename allocator_type::pointer         pointer;
    typedef typename allocator_type::const_pointer   const_pointer;

    typedef implementation-defined                   iterator;
    typedef implementation-defined                   const_iterator;
    typedef std::reverse_iterator<iterator>          reverse_iterator;
    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
    typedef unspecified                              node_type;               // C++17
    typedef INSERT_RETURN_TYPE<iterator, node_type>  insert_return_type;      // C++17

    // construct/copy/destroy:
    set()
        noexcept(
            is_nothrow_default_constructible<allocator_type>::value &&
            is_nothrow_default_constructible<key_compare>::value &&
            is_nothrow_copy_constructible<key_compare>::value);
    explicit set(const value_compare& comp);
    set(const value_compare& comp, const allocator_type& a);
    template <class InputIterator>
        set(InputIterator first, InputIterator last,
            const value_compare& comp = value_compare());
    template <class InputIterator>
        set(InputIterator first, InputIterator last, const value_compare& comp,
            const allocator_type& a);
    template<container-compatible-range<value_type> R>
      set(from_range_t, R&& rg, const Compare& comp = Compare(), const Allocator& = Allocator()); // C++23
    set(const set& s);
    set(set&& s)
        noexcept(
            is_nothrow_move_constructible<allocator_type>::value &&
            is_nothrow_move_constructible<key_compare>::value);
    explicit set(const allocator_type& a);
    set(const set& s, const allocator_type& a);
    set(set&& s, const allocator_type& a);
    set(initializer_list<value_type> il, const value_compare& comp = value_compare());
    set(initializer_list<value_type> il, const value_compare& comp,
        const allocator_type& a);
    template <class InputIterator>
        set(InputIterator first, InputIterator last, const allocator_type& a)
            : set(first, last, Compare(), a) {}  // C++14
    template<container-compatible-range<value_type> R>
      set(from_range_t, R&& rg, const Allocator& a))
        : set(from_range, std::forward<R>(rg), Compare(), a) { } // C++23
    set(initializer_list<value_type> il, const allocator_type& a)
        : set(il, Compare(), a) {}  // C++14
    ~set();

    set& operator=(const set& s);
    set& operator=(set&& s)
        noexcept(
            allocator_type::propagate_on_container_move_assignment::value &&
            is_nothrow_move_assignable<allocator_type>::value &&
            is_nothrow_move_assignable<key_compare>::value);
    set& operator=(initializer_list<value_type> il);

    // iterators:
          iterator begin() noexcept;
    const_iterator begin() const noexcept;
          iterator end() noexcept;
    const_iterator end()   const noexcept;

          reverse_iterator rbegin() noexcept;
    const_reverse_iterator rbegin() const noexcept;
          reverse_iterator rend() noexcept;
    const_reverse_iterator rend()   const noexcept;

    const_iterator         cbegin()  const noexcept;
    const_iterator         cend()    const noexcept;
    const_reverse_iterator crbegin() const noexcept;
    const_reverse_iterator crend()   const noexcept;

    // capacity:
    bool      empty()    const noexcept;
    size_type size()     const noexcept;
    size_type max_size() const noexcept;

    // modifiers:
    template <class... Args>
        pair<iterator, bool> emplace(Args&&... args);
    template <class... Args>
        iterator emplace_hint(const_iterator position, Args&&... args);
    pair<iterator,bool> insert(const value_type& v);
    pair<iterator,bool> insert(value_type&& v);
    iterator insert(const_iterator position, const value_type& v);
    iterator insert(const_iterator position, value_type&& v);
    template <class InputIterator>
        void insert(InputIterator first, InputIterator last);
    template<container-compatible-range<value_type> R>
      void insert_range(R&& rg);                                                      // C++23
    void insert(initializer_list<value_type> il);

    node_type extract(const_iterator position);                                       // C++17
    node_type extract(const key_type& x);                                             // C++17
    insert_return_type insert(node_type&& nh);                                        // C++17
    iterator insert(const_iterator hint, node_type&& nh);                             // C++17

    iterator  erase(const_iterator position);
    iterator  erase(iterator position);  // C++14
    size_type erase(const key_type& k);
    iterator  erase(const_iterator first, const_iterator last);
    void clear() noexcept;

    template<class C2>
      void merge(set<Key, C2, Allocator>& source);         // C++17
    template<class C2>
      void merge(set<Key, C2, Allocator>&& source);        // C++17
    template<class C2>
      void merge(multiset<Key, C2, Allocator>& source);    // C++17
    template<class C2>
      void merge(multiset<Key, C2, Allocator>&& source);   // C++17

    void swap(set& s)
        noexcept(
            __is_nothrow_swappable<key_compare>::value &&
            (!allocator_type::propagate_on_container_swap::value ||
             __is_nothrow_swappable<allocator_type>::value));

    // observers:
    allocator_type get_allocator() const noexcept;
    key_compare    key_comp()      const;
    value_compare  value_comp()    const;

    // set operations:
          iterator find(const key_type& k);
    const_iterator find(const key_type& k) const;
    template<typename K>
        iterator find(const K& x);
    template<typename K>
        const_iterator find(const K& x) const;  // C++14

    template<typename K>
        size_type count(const K& x) const;        // C++14
    size_type      count(const key_type& k) const;

    bool           contains(const key_type& x) const;  // C++20
    template<class K> bool contains(const K& x) const; // C++20

          iterator lower_bound(const key_type& k);
    const_iterator lower_bound(const key_type& k) const;
    template<typename K>
        iterator lower_bound(const K& x);              // C++14
    template<typename K>
        const_iterator lower_bound(const K& x) const;  // C++14

          iterator upper_bound(const key_type& k);
    const_iterator upper_bound(const key_type& k) const;
    template<typename K>
        iterator upper_bound(const K& x);              // C++14
    template<typename K>
        const_iterator upper_bound(const K& x) const;  // C++14
    pair<iterator,iterator>             equal_range(const key_type& k);
    pair<const_iterator,const_iterator> equal_range(const key_type& k) const;
    template<typename K>
        pair<iterator,iterator>             equal_range(const K& x);        // C++14
    template<typename K>
        pair<const_iterator,const_iterator> equal_range(const K& x) const;  // C++14
};

template <class InputIterator,
      class Compare = less<typename iterator_traits<InputIterator>::value_type>,
      class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
set(InputIterator, InputIterator,
    Compare = Compare(), Allocator = Allocator())
  -> set<typename iterator_traits<InputIterator>::value_type, Compare, Allocator>; // C++17

template<ranges::input_range R, class Compare = less<ranges::range_value_t<R>>,
         class Allocator = allocator<ranges::range_value_t<R>>>
  set(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
    -> set<ranges::range_value_t<R>, Compare, Allocator>; // C++23

template<class Key, class Compare = less<Key>, class Allocator = allocator<Key>>
set(initializer_list<Key>, Compare = Compare(), Allocator = Allocator())
  -> set<Key, Compare, Allocator>; // C++17

template<class InputIterator, class Allocator>
set(InputIterator, InputIterator, Allocator)
  -> set<typename iterator_traits<InputIterator>::value_type,
          less<typename iterator_traits<InputIterator>::value_type>, Allocator>; // C++17

template<ranges::input_range R, class Allocator>
  set(from_range_t, R&&, Allocator)
    -> set<ranges::range_value_t<R>, less<ranges::range_value_t<R>>, Allocator>; // C++23

template<class Key, class Allocator>
set(initializer_list<Key>, Allocator) -> set<Key, less<Key>, Allocator>; // C++17

template <class Key, class Compare, class Allocator>
bool
operator==(const set<Key, Compare, Allocator>& x,
           const set<Key, Compare, Allocator>& y);

template <class Key, class Compare, class Allocator>
bool
operator< (const set<Key, Compare, Allocator>& x,
           const set<Key, Compare, Allocator>& y);                                // removed in C++20

template <class Key, class Compare, class Allocator>
bool
operator!=(const set<Key, Compare, Allocator>& x,
           const set<Key, Compare, Allocator>& y);                                // removed in C++20

template <class Key, class Compare, class Allocator>
bool
operator> (const set<Key, Compare, Allocator>& x,
           const set<Key, Compare, Allocator>& y);                                // removed in C++20

template <class Key, class Compare, class Allocator>
bool
operator>=(const set<Key, Compare, Allocator>& x,
           const set<Key, Compare, Allocator>& y);                                // removed in C++20

template <class Key, class Compare, class Allocator>
bool
operator<=(const set<Key, Compare, Allocator>& x,
           const set<Key, Compare, Allocator>& y);                                // removed in C++20

template<class Key, class Compare, class Allocator>
  synth-three-way-result<Key> operator<=>(const set<Key, Compare, Allocator>& x,
                                          const set<Key, Compare, Allocator>& y); // since C++20

// specialized algorithms:
template <class Key, class Compare, class Allocator>
void
swap(set<Key, Compare, Allocator>& x, set<Key, Compare, Allocator>& y)
    noexcept(noexcept(x.swap(y)));

template <class Key, class Compare, class Allocator, class Predicate>
typename set<Key, Compare, Allocator>::size_type
erase_if(set<Key, Compare, Allocator>& c, Predicate pred);  // C++20

template <class Key, class Compare = less<Key>,
          class Allocator = allocator<Key>>
class multiset
{
public:
    // types:
    typedef Key                                      key_type;
    typedef key_type                                 value_type;
    typedef Compare                                  key_compare;
    typedef key_compare                              value_compare;
    typedef Allocator                                allocator_type;
    typedef typename allocator_type::reference       reference;
    typedef typename allocator_type::const_reference const_reference;
    typedef typename allocator_type::size_type       size_type;
    typedef typename allocator_type::difference_type difference_type;
    typedef typename allocator_type::pointer         pointer;
    typedef typename allocator_type::const_pointer   const_pointer;

    typedef implementation-defined                   iterator;
    typedef implementation-defined                   const_iterator;
    typedef std::reverse_iterator<iterator>          reverse_iterator;
    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
    typedef unspecified                              node_type;               // C++17

    // construct/copy/destroy:
    multiset()
        noexcept(
            is_nothrow_default_constructible<allocator_type>::value &&
            is_nothrow_default_constructible<key_compare>::value &&
            is_nothrow_copy_constructible<key_compare>::value);
    explicit multiset(const value_compare& comp);
    multiset(const value_compare& comp, const allocator_type& a);
    template <class InputIterator>
        multiset(InputIterator first, InputIterator last,
                 const value_compare& comp = value_compare());
    template <class InputIterator>
        multiset(InputIterator first, InputIterator last,
                 const value_compare& comp, const allocator_type& a);
    template<container-compatible-range<value_type> R>
      multiset(from_range_t, R&& rg,
               const Compare& comp = Compare(), const Allocator& = Allocator()); // C++23
    multiset(const multiset& s);
    multiset(multiset&& s)
        noexcept(
            is_nothrow_move_constructible<allocator_type>::value &&
            is_nothrow_move_constructible<key_compare>::value);
    explicit multiset(const allocator_type& a);
    multiset(const multiset& s, const allocator_type& a);
    multiset(multiset&& s, const allocator_type& a);
    multiset(initializer_list<value_type> il, const value_compare& comp = value_compare());
    multiset(initializer_list<value_type> il, const value_compare& comp,
             const allocator_type& a);
    template <class InputIterator>
        multiset(InputIterator first, InputIterator last, const allocator_type& a)
            : set(first, last, Compare(), a) {}  // C++14
    template<container-compatible-range<value_type> R>
      multiset(from_range_t, R&& rg, const Allocator& a))
        : multiset(from_range, std::forward<R>(rg), Compare(), a) { } // C++23
    multiset(initializer_list<value_type> il, const allocator_type& a)
        : set(il, Compare(), a) {}  // C++14
    ~multiset();

    multiset& operator=(const multiset& s);
    multiset& operator=(multiset&& s)
        noexcept(
            allocator_type::propagate_on_container_move_assignment::value &&
            is_nothrow_move_assignable<allocator_type>::value &&
            is_nothrow_move_assignable<key_compare>::value);
    multiset& operator=(initializer_list<value_type> il);

    // iterators:
          iterator begin() noexcept;
    const_iterator begin() const noexcept;
          iterator end() noexcept;
    const_iterator end()   const noexcept;

          reverse_iterator rbegin() noexcept;
    const_reverse_iterator rbegin() const noexcept;
          reverse_iterator rend() noexcept;
    const_reverse_iterator rend()   const noexcept;

    const_iterator         cbegin()  const noexcept;
    const_iterator         cend()    const noexcept;
    const_reverse_iterator crbegin() const noexcept;
    const_reverse_iterator crend()   const noexcept;

    // capacity:
    bool      empty()    const noexcept;
    size_type size()     const noexcept;
    size_type max_size() const noexcept;

    // modifiers:
    template <class... Args>
        iterator emplace(Args&&... args);
    template <class... Args>
        iterator emplace_hint(const_iterator position, Args&&... args);
    iterator insert(const value_type& v);
    iterator insert(value_type&& v);
    iterator insert(const_iterator position, const value_type& v);
    iterator insert(const_iterator position, value_type&& v);
    template <class InputIterator>
        void insert(InputIterator first, InputIterator last);
    template<container-compatible-range<value_type> R>
      void insert_range(R&& rg);                                                      // C++23
    void insert(initializer_list<value_type> il);

    node_type extract(const_iterator position);                                       // C++17
    node_type extract(const key_type& x);                                             // C++17
    iterator insert(node_type&& nh);                                                  // C++17
    iterator insert(const_iterator hint, node_type&& nh);                             // C++17

    iterator  erase(const_iterator position);
    iterator  erase(iterator position);  // C++14
    size_type erase(const key_type& k);
    iterator  erase(const_iterator first, const_iterator last);
    void clear() noexcept;

    template<class C2>
      void merge(multiset<Key, C2, Allocator>& source);    // C++17
    template<class C2>
      void merge(multiset<Key, C2, Allocator>&& source);   // C++17
    template<class C2>
      void merge(set<Key, C2, Allocator>& source);         // C++17
    template<class C2>
      void merge(set<Key, C2, Allocator>&& source);        // C++17

    void swap(multiset& s)
        noexcept(
            __is_nothrow_swappable<key_compare>::value &&
            (!allocator_type::propagate_on_container_swap::value ||
             __is_nothrow_swappable<allocator_type>::value));

    // observers:
    allocator_type get_allocator() const noexcept;
    key_compare    key_comp()      const;
    value_compare  value_comp()    const;

    // set operations:
          iterator find(const key_type& k);
    const_iterator find(const key_type& k) const;
    template<typename K>
        iterator find(const K& x);
    template<typename K>
        const_iterator find(const K& x) const;  // C++14

    template<typename K>
        size_type count(const K& x) const;      // C++14
    size_type      count(const key_type& k) const;

    bool           contains(const key_type& x) const;  // C++20
    template<class K> bool contains(const K& x) const; // C++20

          iterator lower_bound(const key_type& k);
    const_iterator lower_bound(const key_type& k) const;
    template<typename K>
        iterator lower_bound(const K& x);              // C++14
    template<typename K>
        const_iterator lower_bound(const K& x) const;  // C++14

          iterator upper_bound(const key_type& k);
    const_iterator upper_bound(const key_type& k) const;
    template<typename K>
        iterator upper_bound(const K& x);              // C++14
    template<typename K>
        const_iterator upper_bound(const K& x) const;  // C++14

    pair<iterator,iterator>             equal_range(const key_type& k);
    pair<const_iterator,const_iterator> equal_range(const key_type& k) const;
    template<typename K>
        pair<iterator,iterator>             equal_range(const K& x);        // C++14
    template<typename K>
        pair<const_iterator,const_iterator> equal_range(const K& x) const;  // C++14
};

template <class InputIterator,
      class Compare = less<typename iterator_traits<InputIterator>::value_type>,
      class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
multiset(InputIterator, InputIterator,
    Compare = Compare(), Allocator = Allocator())
  -> multiset<typename iterator_traits<InputIterator>::value_type, Compare, Allocator>; // C++17

template<ranges::input_range R, class Compare = less<ranges::range_value_t<R>>,
          class Allocator = allocator<ranges::range_value_t<R>>>
  multiset(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
    -> multiset<ranges::range_value_t<R>, Compare, Allocator>;

template<class Key, class Compare = less<Key>, class Allocator = allocator<Key>>
multiset(initializer_list<Key>, Compare = Compare(), Allocator = Allocator())
  -> multiset<Key, Compare, Allocator>; // C++17

template<class InputIterator, class Allocator>
multiset(InputIterator, InputIterator, Allocator)
  -> multiset<typename iterator_traits<InputIterator>::value_type,
          less<typename iterator_traits<InputIterator>::value_type>, Allocator>; // C++17

template<ranges::input_range R, class Allocator>
  multiset(from_range_t, R&&, Allocator)
    -> multiset<ranges::range_value_t<R>, less<ranges::range_value_t<R>>, Allocator>;

template<class Key, class Allocator>
multiset(initializer_list<Key>, Allocator) -> multiset<Key, less<Key>, Allocator>; // C++17

template <class Key, class Compare, class Allocator>
bool
operator==(const multiset<Key, Compare, Allocator>& x,
           const multiset<Key, Compare, Allocator>& y);

template <class Key, class Compare, class Allocator>
bool
operator< (const multiset<Key, Compare, Allocator>& x,
           const multiset<Key, Compare, Allocator>& y);                                // removed in C++20

template <class Key, class Compare, class Allocator>
bool
operator!=(const multiset<Key, Compare, Allocator>& x,
           const multiset<Key, Compare, Allocator>& y);                                // removed in C++20

template <class Key, class Compare, class Allocator>
bool
operator> (const multiset<Key, Compare, Allocator>& x,
           const multiset<Key, Compare, Allocator>& y);                                // removed in C++20

template <class Key, class Compare, class Allocator>
bool
operator>=(const multiset<Key, Compare, Allocator>& x,
           const multiset<Key, Compare, Allocator>& y);                                // removed in C++20

template <class Key, class Compare, class Allocator>
bool
operator<=(const multiset<Key, Compare, Allocator>& x,
           const multiset<Key, Compare, Allocator>& y);                                // removed in C++20

template<class Key, class Compare, class Allocator>
  synth-three-way-result<Key> operator<=>(const multiset<Key, Compare, Allocator>& x,
                                          const multiset<Key, Compare, Allocator>& y); // since C++20

// specialized algorithms:
template <class Key, class Compare, class Allocator>
void
swap(multiset<Key, Compare, Allocator>& x, multiset<Key, Compare, Allocator>& y)
    noexcept(noexcept(x.swap(y)));

template <class Key, class Compare, class Allocator, class Predicate>
typename multiset<Key, Compare, Allocator>::size_type
erase_if(multiset<Key, Compare, Allocator>& c, Predicate pred);  // C++20

}  // std

*/

#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
#  include <__cxx03/set>
#else
#  include <__algorithm/equal.h>
#  include <__algorithm/lexicographical_compare.h>
#  include <__algorithm/lexicographical_compare_three_way.h>
#  include <__assert>
#  include <__config>
#  include <__functional/is_transparent.h>
#  include <__functional/operations.h>
#  include <__fwd/set.h>
#  include <__iterator/erase_if_container.h>
#  include <__iterator/iterator_traits.h>
#  include <__iterator/ranges_iterator_traits.h>
#  include <__iterator/reverse_iterator.h>
#  include <__memory/allocator.h>
#  include <__memory/allocator_traits.h>
#  include <__memory_resource/polymorphic_allocator.h>
#  include <__node_handle>
#  include <__ranges/concepts.h>
#  include <__ranges/container_compatible_range.h>
#  include <__ranges/from_range.h>
#  include <__tree>
#  include <__type_traits/container_traits.h>
#  include <__type_traits/enable_if.h>
#  include <__type_traits/is_allocator.h>
#  include <__type_traits/is_nothrow_assignable.h>
#  include <__type_traits/is_nothrow_constructible.h>
#  include <__type_traits/is_same.h>
#  include <__type_traits/is_swappable.h>
#  include <__type_traits/type_identity.h>
#  include <__utility/forward.h>
#  include <__utility/move.h>
#  include <__utility/pair.h>
#  include <version>

// standard-mandated includes

// [iterator.range]
#  include <__iterator/access.h>
#  include <__iterator/data.h>
#  include <__iterator/empty.h>
#  include <__iterator/reverse_access.h>
#  include <__iterator/size.h>

// [associative.set.syn]
#  include <compare>
#  include <initializer_list>

#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#    pragma GCC system_header
#  endif

_LIBCPP_PUSH_MACROS
#  include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Key, class _Compare, class _Allocator>
class set {
public:
  // types:
  typedef _Key key_type;
  typedef key_type value_type;
  typedef __type_identity_t<_Compare> key_compare;
  typedef key_compare value_compare;
  typedef __type_identity_t<_Allocator> allocator_type;
  typedef value_type& reference;
  typedef const value_type& const_reference;

  static_assert(is_same<typename allocator_type::value_type, value_type>::value,
                "Allocator::value_type must be same type as value_type");

private:
  typedef __tree<value_type, value_compare, allocator_type> __base;
  typedef allocator_traits<allocator_type> __alloc_traits;

  static_assert(__check_valid_allocator<allocator_type>::value, "");

  __base __tree_;

public:
  typedef typename __base::pointer pointer;
  typedef typename __base::const_pointer const_pointer;
  typedef typename __base::size_type size_type;
  typedef typename __base::difference_type difference_type;
  typedef typename __base::const_iterator iterator;
  typedef typename __base::const_iterator const_iterator;
  typedef std::reverse_iterator<iterator> reverse_iterator;
  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;

#  if _LIBCPP_STD_VER >= 17
  typedef __set_node_handle<typename __base::__node, allocator_type> node_type;
  typedef __insert_return_type<iterator, node_type> insert_return_type;
#  endif

  template <class _Key2, class _Compare2, class _Alloc2>
  friend class set;
  template <class _Key2, class _Compare2, class _Alloc2>
  friend class multiset;

  _LIBCPP_HIDE_FROM_ABI set() _NOEXCEPT_(
      is_nothrow_default_constructible<allocator_type>::value&& is_nothrow_default_constructible<key_compare>::value&&
          is_nothrow_copy_constructible<key_compare>::value)
      : __tree_(value_compare()) {}

  _LIBCPP_HIDE_FROM_ABI explicit set(const value_compare& __comp) _NOEXCEPT_(
      is_nothrow_default_constructible<allocator_type>::value&& is_nothrow_copy_constructible<key_compare>::value)
      : __tree_(__comp) {}

  _LIBCPP_HIDE_FROM_ABI explicit set(const value_compare& __comp, const allocator_type& __a) : __tree_(__comp, __a) {}
  template <class _InputIterator>
  _LIBCPP_HIDE_FROM_ABI set(_InputIterator __f, _InputIterator __l, const value_compare& __comp = value_compare())
      : __tree_(__comp) {
    insert(__f, __l);
  }

  template <class _InputIterator>
  _LIBCPP_HIDE_FROM_ABI
  set(_InputIterator __f, _InputIterator __l, const value_compare& __comp, const allocator_type& __a)
      : __tree_(__comp, __a) {
    insert(__f, __l);
  }

#  if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<value_type> _Range>
  _LIBCPP_HIDE_FROM_ABI
  set(from_range_t,
      _Range&& __range,
      const key_compare& __comp = key_compare(),
      const allocator_type& __a = allocator_type())
      : __tree_(__comp, __a) {
    insert_range(std::forward<_Range>(__range));
  }
#  endif

#  if _LIBCPP_STD_VER >= 14
  template <class _InputIterator>
  _LIBCPP_HIDE_FROM_ABI set(_InputIterator __f, _InputIterator __l, const allocator_type& __a)
      : set(__f, __l, key_compare(), __a) {}
#  endif

#  if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<value_type> _Range>
  _LIBCPP_HIDE_FROM_ABI set(from_range_t, _Range&& __range, const allocator_type& __a)
      : set(from_range, std::forward<_Range>(__range), key_compare(), __a) {}
#  endif

  _LIBCPP_HIDE_FROM_ABI set(const set& __s) : __tree_(__s.__tree_) { insert(__s.begin(), __s.end()); }

  _LIBCPP_HIDE_FROM_ABI set& operator=(const set& __s) {
    __tree_ = __s.__tree_;
    return *this;
  }

#  ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI set(set&& __s) noexcept(is_nothrow_move_constructible<__base>::value)
      : __tree_(std::move(__s.__tree_)) {}
#  endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI explicit set(const allocator_type& __a) : __tree_(__a) {}

  _LIBCPP_HIDE_FROM_ABI set(const set& __s, const allocator_type& __a) : __tree_(__s.__tree_.value_comp(), __a) {
    insert(__s.begin(), __s.end());
  }

#  ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI set(set&& __s, const allocator_type& __a);

  _LIBCPP_HIDE_FROM_ABI set(initializer_list<value_type> __il, const value_compare& __comp = value_compare())
      : __tree_(__comp) {
    insert(__il.begin(), __il.end());
  }

  _LIBCPP_HIDE_FROM_ABI set(initializer_list<value_type> __il, const value_compare& __comp, const allocator_type& __a)
      : __tree_(__comp, __a) {
    insert(__il.begin(), __il.end());
  }

#    if _LIBCPP_STD_VER >= 14
  _LIBCPP_HIDE_FROM_ABI set(initializer_list<value_type> __il, const allocator_type& __a)
      : set(__il, key_compare(), __a) {}
#    endif

  _LIBCPP_HIDE_FROM_ABI set& operator=(initializer_list<value_type> __il) {
    __tree_.__assign_unique(__il.begin(), __il.end());
    return *this;
  }

  _LIBCPP_HIDE_FROM_ABI set& operator=(set&& __s) noexcept(is_nothrow_move_assignable<__base>::value) {
    __tree_ = std::move(__s.__tree_);
    return *this;
  }
#  endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI ~set() { static_assert(sizeof(std::__diagnose_non_const_comparator<_Key, _Compare>()), ""); }

  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __tree_.begin(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __tree_.begin(); }
  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __tree_.end(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __tree_.end(); }

  _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT { return reverse_iterator(end()); }
  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT { return const_reverse_iterator(end()); }
  _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT { return reverse_iterator(begin()); }
  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT { return const_reverse_iterator(begin()); }

  _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return begin(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return end(); }
  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT { return rbegin(); }
  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT { return rend(); }

  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __tree_.size() == 0; }
  _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __tree_.size(); }
  _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { return __tree_.max_size(); }

  // modifiers:
#  ifndef _LIBCPP_CXX03_LANG
  template <class... _Args>
  _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> emplace(_Args&&... __args) {
    return __tree_.__emplace_unique(std::forward<_Args>(__args)...);
  }
  template <class... _Args>
  _LIBCPP_HIDE_FROM_ABI iterator emplace_hint(const_iterator __p, _Args&&... __args) {
    return __tree_.__emplace_hint_unique(__p, std::forward<_Args>(__args)...);
  }
#  endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> insert(const value_type& __v) { return __tree_.__insert_unique(__v); }
  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, const value_type& __v) {
    return __tree_.__insert_unique(__p, __v);
  }

  template <class _InputIterator>
  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __f, _InputIterator __l) {
    for (const_iterator __e = cend(); __f != __l; ++__f)
      __tree_.__insert_unique(__e, *__f);
  }

#  if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<value_type> _Range>
  _LIBCPP_HIDE_FROM_ABI void insert_range(_Range&& __range) {
    const_iterator __end = cend();
    for (auto&& __element : __range) {
      __tree_.__insert_unique(__end, std::forward<decltype(__element)>(__element));
    }
  }
#  endif

#  ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> insert(value_type&& __v) {
    return __tree_.__insert_unique(std::move(__v));
  }

  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, value_type&& __v) {
    return __tree_.__insert_unique(__p, std::move(__v));
  }

  _LIBCPP_HIDE_FROM_ABI void insert(initializer_list<value_type> __il) { insert(__il.begin(), __il.end()); }
#  endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __p) { return __tree_.erase(__p); }
  _LIBCPP_HIDE_FROM_ABI size_type erase(const key_type& __k) { return __tree_.__erase_unique(__k); }
  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __f, const_iterator __l) { return __tree_.erase(__f, __l); }
  _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT { __tree_.clear(); }

#  if _LIBCPP_STD_VER >= 17
  _LIBCPP_HIDE_FROM_ABI insert_return_type insert(node_type&& __nh) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
                                        "node_type with incompatible allocator passed to set::insert()");
    return __tree_.template __node_handle_insert_unique< node_type, insert_return_type>(std::move(__nh));
  }
  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __hint, node_type&& __nh) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
                                        "node_type with incompatible allocator passed to set::insert()");
    return __tree_.template __node_handle_insert_unique<node_type>(__hint, std::move(__nh));
  }
  _LIBCPP_HIDE_FROM_ABI node_type extract(key_type const& __key) {
    return __tree_.template __node_handle_extract<node_type>(__key);
  }
  _LIBCPP_HIDE_FROM_ABI node_type extract(const_iterator __it) {
    return __tree_.template __node_handle_extract<node_type>(__it);
  }
  template <class _Compare2>
  _LIBCPP_HIDE_FROM_ABI void merge(set<key_type, _Compare2, allocator_type>& __source) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
    __tree_.__node_handle_merge_unique(__source.__tree_);
  }
  template <class _Compare2>
  _LIBCPP_HIDE_FROM_ABI void merge(set<key_type, _Compare2, allocator_type>&& __source) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
    __tree_.__node_handle_merge_unique(__source.__tree_);
  }
  template <class _Compare2>
  _LIBCPP_HIDE_FROM_ABI void merge(multiset<key_type, _Compare2, allocator_type>& __source) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
    __tree_.__node_handle_merge_unique(__source.__tree_);
  }
  template <class _Compare2>
  _LIBCPP_HIDE_FROM_ABI void merge(multiset<key_type, _Compare2, allocator_type>&& __source) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
    __tree_.__node_handle_merge_unique(__source.__tree_);
  }
#  endif

  _LIBCPP_HIDE_FROM_ABI void swap(set& __s) _NOEXCEPT_(__is_nothrow_swappable_v<__base>) { __tree_.swap(__s.__tree_); }

  _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT { return __tree_.__alloc(); }
  _LIBCPP_HIDE_FROM_ABI key_compare key_comp() const { return __tree_.value_comp(); }
  _LIBCPP_HIDE_FROM_ABI value_compare value_comp() const { return __tree_.value_comp(); }

  // set operations:
  _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) { return __tree_.find(__k); }
  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const { return __tree_.find(__k); }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI iterator find(const _K2& __k) {
    return __tree_.find(__k);
  }
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI const_iterator find(const _K2& __k) const {
    return __tree_.find(__k);
  }
#  endif

  _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __tree_.__count_unique(__k); }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI size_type count(const _K2& __k) const {
    return __tree_.__count_multi(__k);
  }
#  endif

#  if _LIBCPP_STD_VER >= 20
  _LIBCPP_HIDE_FROM_ABI bool contains(const key_type& __k) const { return find(__k) != end(); }
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI bool contains(const _K2& __k) const {
    return find(__k) != end();
  }
#  endif // _LIBCPP_STD_VER >= 20

  _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const key_type& __k) { return __tree_.lower_bound(__k); }
  _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const key_type& __k) const { return __tree_.lower_bound(__k); }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const _K2& __k) {
    return __tree_.lower_bound(__k);
  }

  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const _K2& __k) const {
    return __tree_.lower_bound(__k);
  }
#  endif

  _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const key_type& __k) { return __tree_.upper_bound(__k); }
  _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const key_type& __k) const { return __tree_.upper_bound(__k); }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const _K2& __k) {
    return __tree_.upper_bound(__k);
  }
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const _K2& __k) const {
    return __tree_.upper_bound(__k);
  }
#  endif

  _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> equal_range(const key_type& __k) {
    return __tree_.__equal_range_unique(__k);
  }
  _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> equal_range(const key_type& __k) const {
    return __tree_.__equal_range_unique(__k);
  }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> equal_range(const _K2& __k) {
    return __tree_.__equal_range_multi(__k);
  }
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> equal_range(const _K2& __k) const {
    return __tree_.__equal_range_multi(__k);
  }
#  endif
};

#  if _LIBCPP_STD_VER >= 17
template <class _InputIterator,
          class _Compare   = less<__iter_value_type<_InputIterator>>,
          class _Allocator = allocator<__iter_value_type<_InputIterator>>,
          class            = enable_if_t<__has_input_iterator_category<_InputIterator>::value, void>,
          class            = enable_if_t<__is_allocator<_Allocator>::value, void>,
          class            = enable_if_t<!__is_allocator<_Compare>::value, void>>
set(_InputIterator, _InputIterator, _Compare = _Compare(), _Allocator = _Allocator())
    -> set<__iter_value_type<_InputIterator>, _Compare, _Allocator>;

#    if _LIBCPP_STD_VER >= 23
template <ranges::input_range _Range,
          class _Compare   = less<ranges::range_value_t<_Range>>,
          class _Allocator = allocator<ranges::range_value_t<_Range>>,
          class            = enable_if_t<__is_allocator<_Allocator>::value, void>,
          class            = enable_if_t<!__is_allocator<_Compare>::value, void>>
set(from_range_t, _Range&&, _Compare = _Compare(), _Allocator = _Allocator())
    -> set<ranges::range_value_t<_Range>, _Compare, _Allocator>;
#    endif

template <class _Key,
          class _Compare   = less<_Key>,
          class _Allocator = allocator<_Key>,
          class            = enable_if_t<!__is_allocator<_Compare>::value, void>,
          class            = enable_if_t<__is_allocator<_Allocator>::value, void>>
set(initializer_list<_Key>, _Compare = _Compare(), _Allocator = _Allocator()) -> set<_Key, _Compare, _Allocator>;

template <class _InputIterator,
          class _Allocator,
          class = enable_if_t<__has_input_iterator_category<_InputIterator>::value, void>,
          class = enable_if_t<__is_allocator<_Allocator>::value, void>>
set(_InputIterator,
    _InputIterator,
    _Allocator) -> set<__iter_value_type<_InputIterator>, less<__iter_value_type<_InputIterator>>, _Allocator>;

#    if _LIBCPP_STD_VER >= 23
template <ranges::input_range _Range, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value, void>>
set(from_range_t,
    _Range&&,
    _Allocator) -> set<ranges::range_value_t<_Range>, less<ranges::range_value_t<_Range>>, _Allocator>;
#    endif

template <class _Key, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value, void>>
set(initializer_list<_Key>, _Allocator) -> set<_Key, less<_Key>, _Allocator>;
#  endif

#  ifndef _LIBCPP_CXX03_LANG

template <class _Key, class _Compare, class _Allocator>
set<_Key, _Compare, _Allocator>::set(set&& __s, const allocator_type& __a) : __tree_(std::move(__s.__tree_), __a) {
  if (__a != __s.get_allocator()) {
    const_iterator __e = cend();
    while (!__s.empty())
      insert(__e, std::move(__s.__tree_.remove(__s.begin())->__value_));
  }
}

#  endif // _LIBCPP_CXX03_LANG

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator==(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
  return __x.size() == __y.size() && std::equal(__x.begin(), __x.end(), __y.begin());
}

#  if _LIBCPP_STD_VER <= 17

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator<(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
  return std::lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end());
}

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator!=(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
  return !(__x == __y);
}

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator>(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
  return __y < __x;
}

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator>=(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
  return !(__x < __y);
}

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator<=(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
  return !(__y < __x);
}

#  else // _LIBCPP_STD_VER <= 17

template <class _Key, class _Compare, class _Allocator>
_LIBCPP_HIDE_FROM_ABI __synth_three_way_result<_Key>
operator<=>(const set<_Key, _Compare, _Allocator>& __x, const set<_Key, _Compare, _Allocator>& __y) {
  return std::lexicographical_compare_three_way(__x.begin(), __x.end(), __y.begin(), __y.end(), std::__synth_three_way);
}

#  endif // _LIBCPP_STD_VER <= 17

// specialized algorithms:
template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI void swap(set<_Key, _Compare, _Allocator>& __x, set<_Key, _Compare, _Allocator>& __y)
    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y))) {
  __x.swap(__y);
}

#  if _LIBCPP_STD_VER >= 20
template <class _Key, class _Compare, class _Allocator, class _Predicate>
inline _LIBCPP_HIDE_FROM_ABI typename set<_Key, _Compare, _Allocator>::size_type
erase_if(set<_Key, _Compare, _Allocator>& __c, _Predicate __pred) {
  return std::__libcpp_erase_if_container(__c, __pred);
}
#  endif

template <class _Key, class _Compare, class _Allocator>
struct __container_traits<set<_Key, _Compare, _Allocator> > {
  // http://eel.is/c++draft/associative.reqmts.except#2
  // For associative containers, if an exception is thrown by any operation from within
  // an insert or emplace function inserting a single element, the insertion has no effect.
  static _LIBCPP_CONSTEXPR const bool __emplacement_has_strong_exception_safety_guarantee = true;
};

template <class _Key, class _Compare, class _Allocator>
class multiset {
public:
  // types:
  typedef _Key key_type;
  typedef key_type value_type;
  typedef __type_identity_t<_Compare> key_compare;
  typedef key_compare value_compare;
  typedef __type_identity_t<_Allocator> allocator_type;
  typedef value_type& reference;
  typedef const value_type& const_reference;

  static_assert(is_same<typename allocator_type::value_type, value_type>::value,
                "Allocator::value_type must be same type as value_type");

private:
  typedef __tree<value_type, value_compare, allocator_type> __base;
  typedef allocator_traits<allocator_type> __alloc_traits;

  static_assert(__check_valid_allocator<allocator_type>::value, "");

  __base __tree_;

public:
  typedef typename __base::pointer pointer;
  typedef typename __base::const_pointer const_pointer;
  typedef typename __base::size_type size_type;
  typedef typename __base::difference_type difference_type;
  typedef typename __base::const_iterator iterator;
  typedef typename __base::const_iterator const_iterator;
  typedef std::reverse_iterator<iterator> reverse_iterator;
  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;

#  if _LIBCPP_STD_VER >= 17
  typedef __set_node_handle<typename __base::__node, allocator_type> node_type;
#  endif

  template <class _Key2, class _Compare2, class _Alloc2>
  friend class set;
  template <class _Key2, class _Compare2, class _Alloc2>
  friend class multiset;

  // construct/copy/destroy:
  _LIBCPP_HIDE_FROM_ABI multiset() _NOEXCEPT_(
      is_nothrow_default_constructible<allocator_type>::value&& is_nothrow_default_constructible<key_compare>::value&&
          is_nothrow_copy_constructible<key_compare>::value)
      : __tree_(value_compare()) {}

  _LIBCPP_HIDE_FROM_ABI explicit multiset(const value_compare& __comp) _NOEXCEPT_(
      is_nothrow_default_constructible<allocator_type>::value&& is_nothrow_copy_constructible<key_compare>::value)
      : __tree_(__comp) {}

  _LIBCPP_HIDE_FROM_ABI explicit multiset(const value_compare& __comp, const allocator_type& __a)
      : __tree_(__comp, __a) {}
  template <class _InputIterator>
  _LIBCPP_HIDE_FROM_ABI multiset(_InputIterator __f, _InputIterator __l, const value_compare& __comp = value_compare())
      : __tree_(__comp) {
    insert(__f, __l);
  }

#  if _LIBCPP_STD_VER >= 14
  template <class _InputIterator>
  _LIBCPP_HIDE_FROM_ABI multiset(_InputIterator __f, _InputIterator __l, const allocator_type& __a)
      : multiset(__f, __l, key_compare(), __a) {}
#  endif

  template <class _InputIterator>
  _LIBCPP_HIDE_FROM_ABI
  multiset(_InputIterator __f, _InputIterator __l, const value_compare& __comp, const allocator_type& __a)
      : __tree_(__comp, __a) {
    insert(__f, __l);
  }

#  if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<value_type> _Range>
  _LIBCPP_HIDE_FROM_ABI
  multiset(from_range_t,
           _Range&& __range,
           const key_compare& __comp = key_compare(),
           const allocator_type& __a = allocator_type())
      : __tree_(__comp, __a) {
    insert_range(std::forward<_Range>(__range));
  }

  template <_ContainerCompatibleRange<value_type> _Range>
  _LIBCPP_HIDE_FROM_ABI multiset(from_range_t, _Range&& __range, const allocator_type& __a)
      : multiset(from_range, std::forward<_Range>(__range), key_compare(), __a) {}
#  endif

  _LIBCPP_HIDE_FROM_ABI multiset(const multiset& __s)
      : __tree_(__s.__tree_.value_comp(),
                __alloc_traits::select_on_container_copy_construction(__s.__tree_.__alloc())) {
    insert(__s.begin(), __s.end());
  }

  _LIBCPP_HIDE_FROM_ABI multiset& operator=(const multiset& __s) {
    __tree_ = __s.__tree_;
    return *this;
  }

#  ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI multiset(multiset&& __s) noexcept(is_nothrow_move_constructible<__base>::value)
      : __tree_(std::move(__s.__tree_)) {}

  _LIBCPP_HIDE_FROM_ABI multiset(multiset&& __s, const allocator_type& __a);
#  endif // _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI explicit multiset(const allocator_type& __a) : __tree_(__a) {}
  _LIBCPP_HIDE_FROM_ABI multiset(const multiset& __s, const allocator_type& __a)
      : __tree_(__s.__tree_.value_comp(), __a) {
    insert(__s.begin(), __s.end());
  }

#  ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI multiset(initializer_list<value_type> __il, const value_compare& __comp = value_compare())
      : __tree_(__comp) {
    insert(__il.begin(), __il.end());
  }

  _LIBCPP_HIDE_FROM_ABI
  multiset(initializer_list<value_type> __il, const value_compare& __comp, const allocator_type& __a)
      : __tree_(__comp, __a) {
    insert(__il.begin(), __il.end());
  }

#    if _LIBCPP_STD_VER >= 14
  _LIBCPP_HIDE_FROM_ABI multiset(initializer_list<value_type> __il, const allocator_type& __a)
      : multiset(__il, key_compare(), __a) {}
#    endif

  _LIBCPP_HIDE_FROM_ABI multiset& operator=(initializer_list<value_type> __il) {
    __tree_.__assign_multi(__il.begin(), __il.end());
    return *this;
  }

  _LIBCPP_HIDE_FROM_ABI multiset& operator=(multiset&& __s) _NOEXCEPT_(is_nothrow_move_assignable<__base>::value) {
    __tree_ = std::move(__s.__tree_);
    return *this;
  }
#  endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI ~multiset() {
    static_assert(sizeof(std::__diagnose_non_const_comparator<_Key, _Compare>()), "");
  }

  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __tree_.begin(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __tree_.begin(); }
  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __tree_.end(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __tree_.end(); }

  _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT { return reverse_iterator(end()); }
  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT { return const_reverse_iterator(end()); }
  _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT { return reverse_iterator(begin()); }
  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT { return const_reverse_iterator(begin()); }

  _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return begin(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return end(); }
  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT { return rbegin(); }
  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT { return rend(); }

  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __tree_.size() == 0; }
  _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __tree_.size(); }
  _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { return __tree_.max_size(); }

  // modifiers:
#  ifndef _LIBCPP_CXX03_LANG
  template <class... _Args>
  _LIBCPP_HIDE_FROM_ABI iterator emplace(_Args&&... __args) {
    return __tree_.__emplace_multi(std::forward<_Args>(__args)...);
  }
  template <class... _Args>
  _LIBCPP_HIDE_FROM_ABI iterator emplace_hint(const_iterator __p, _Args&&... __args) {
    return __tree_.__emplace_hint_multi(__p, std::forward<_Args>(__args)...);
  }
#  endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI iterator insert(const value_type& __v) { return __tree_.__insert_multi(__v); }
  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, const value_type& __v) {
    return __tree_.__insert_multi(__p, __v);
  }

  template <class _InputIterator>
  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __f, _InputIterator __l) {
    for (const_iterator __e = cend(); __f != __l; ++__f)
      __tree_.__insert_multi(__e, *__f);
  }

#  if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<value_type> _Range>
  _LIBCPP_HIDE_FROM_ABI void insert_range(_Range&& __range) {
    const_iterator __end = cend();
    for (auto&& __element : __range) {
      __tree_.__insert_multi(__end, std::forward<decltype(__element)>(__element));
    }
  }
#  endif

#  ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI iterator insert(value_type&& __v) { return __tree_.__insert_multi(std::move(__v)); }

  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, value_type&& __v) {
    return __tree_.__insert_multi(__p, std::move(__v));
  }

  _LIBCPP_HIDE_FROM_ABI void insert(initializer_list<value_type> __il) { insert(__il.begin(), __il.end()); }
#  endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __p) { return __tree_.erase(__p); }
  _LIBCPP_HIDE_FROM_ABI size_type erase(const key_type& __k) { return __tree_.__erase_multi(__k); }
  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __f, const_iterator __l) { return __tree_.erase(__f, __l); }
  _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT { __tree_.clear(); }

#  if _LIBCPP_STD_VER >= 17
  _LIBCPP_HIDE_FROM_ABI iterator insert(node_type&& __nh) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
                                        "node_type with incompatible allocator passed to multiset::insert()");
    return __tree_.template __node_handle_insert_multi<node_type>(std::move(__nh));
  }
  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __hint, node_type&& __nh) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
                                        "node_type with incompatible allocator passed to multiset::insert()");
    return __tree_.template __node_handle_insert_multi<node_type>(__hint, std::move(__nh));
  }
  _LIBCPP_HIDE_FROM_ABI node_type extract(key_type const& __key) {
    return __tree_.template __node_handle_extract<node_type>(__key);
  }
  _LIBCPP_HIDE_FROM_ABI node_type extract(const_iterator __it) {
    return __tree_.template __node_handle_extract<node_type>(__it);
  }
  template <class _Compare2>
  _LIBCPP_HIDE_FROM_ABI void merge(multiset<key_type, _Compare2, allocator_type>& __source) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
    __tree_.__node_handle_merge_multi(__source.__tree_);
  }
  template <class _Compare2>
  _LIBCPP_HIDE_FROM_ABI void merge(multiset<key_type, _Compare2, allocator_type>&& __source) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
    __tree_.__node_handle_merge_multi(__source.__tree_);
  }
  template <class _Compare2>
  _LIBCPP_HIDE_FROM_ABI void merge(set<key_type, _Compare2, allocator_type>& __source) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
    __tree_.__node_handle_merge_multi(__source.__tree_);
  }
  template <class _Compare2>
  _LIBCPP_HIDE_FROM_ABI void merge(set<key_type, _Compare2, allocator_type>&& __source) {
    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
    __tree_.__node_handle_merge_multi(__source.__tree_);
  }
#  endif

  _LIBCPP_HIDE_FROM_ABI void swap(multiset& __s) _NOEXCEPT_(__is_nothrow_swappable_v<__base>) {
    __tree_.swap(__s.__tree_);
  }

  _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT { return __tree_.__alloc(); }
  _LIBCPP_HIDE_FROM_ABI key_compare key_comp() const { return __tree_.value_comp(); }
  _LIBCPP_HIDE_FROM_ABI value_compare value_comp() const { return __tree_.value_comp(); }

  // set operations:
  _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) { return __tree_.find(__k); }
  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const { return __tree_.find(__k); }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI iterator find(const _K2& __k) {
    return __tree_.find(__k);
  }
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI const_iterator find(const _K2& __k) const {
    return __tree_.find(__k);
  }
#  endif

  _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __tree_.__count_multi(__k); }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI size_type count(const _K2& __k) const {
    return __tree_.__count_multi(__k);
  }
#  endif

#  if _LIBCPP_STD_VER >= 20
  _LIBCPP_HIDE_FROM_ABI bool contains(const key_type& __k) const { return find(__k) != end(); }
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI bool contains(const _K2& __k) const {
    return find(__k) != end();
  }
#  endif // _LIBCPP_STD_VER >= 20

  _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const key_type& __k) { return __tree_.lower_bound(__k); }
  _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const key_type& __k) const { return __tree_.lower_bound(__k); }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const _K2& __k) {
    return __tree_.lower_bound(__k);
  }

  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const _K2& __k) const {
    return __tree_.lower_bound(__k);
  }
#  endif

  _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const key_type& __k) { return __tree_.upper_bound(__k); }
  _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const key_type& __k) const { return __tree_.upper_bound(__k); }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const _K2& __k) {
    return __tree_.upper_bound(__k);
  }
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const _K2& __k) const {
    return __tree_.upper_bound(__k);
  }
#  endif

  _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> equal_range(const key_type& __k) {
    return __tree_.__equal_range_multi(__k);
  }
  _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> equal_range(const key_type& __k) const {
    return __tree_.__equal_range_multi(__k);
  }
#  if _LIBCPP_STD_VER >= 14
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> equal_range(const _K2& __k) {
    return __tree_.__equal_range_multi(__k);
  }
  template <typename _K2, enable_if_t<__is_transparent_v<_Compare, _K2>, int> = 0>
  _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> equal_range(const _K2& __k) const {
    return __tree_.__equal_range_multi(__k);
  }
#  endif
};

#  if _LIBCPP_STD_VER >= 17
template <class _InputIterator,
          class _Compare   = less<__iter_value_type<_InputIterator>>,
          class _Allocator = allocator<__iter_value_type<_InputIterator>>,
          class            = enable_if_t<__has_input_iterator_category<_InputIterator>::value, void>,
          class            = enable_if_t<__is_allocator<_Allocator>::value, void>,
          class            = enable_if_t<!__is_allocator<_Compare>::value, void>>
multiset(_InputIterator, _InputIterator, _Compare = _Compare(), _Allocator = _Allocator())
    -> multiset<__iter_value_type<_InputIterator>, _Compare, _Allocator>;

#    if _LIBCPP_STD_VER >= 23
template <ranges::input_range _Range,
          class _Compare   = less<ranges::range_value_t<_Range>>,
          class _Allocator = allocator<ranges::range_value_t<_Range>>,
          class            = enable_if_t<__is_allocator<_Allocator>::value, void>,
          class            = enable_if_t<!__is_allocator<_Compare>::value, void>>
multiset(from_range_t, _Range&&, _Compare = _Compare(), _Allocator = _Allocator())
    -> multiset<ranges::range_value_t<_Range>, _Compare, _Allocator>;
#    endif

template <class _Key,
          class _Compare   = less<_Key>,
          class _Allocator = allocator<_Key>,
          class            = enable_if_t<__is_allocator<_Allocator>::value, void>,
          class            = enable_if_t<!__is_allocator<_Compare>::value, void>>
multiset(initializer_list<_Key>,
         _Compare   = _Compare(),
         _Allocator = _Allocator()) -> multiset<_Key, _Compare, _Allocator>;

template <class _InputIterator,
          class _Allocator,
          class = enable_if_t<__has_input_iterator_category<_InputIterator>::value, void>,
          class = enable_if_t<__is_allocator<_Allocator>::value, void>>
multiset(_InputIterator, _InputIterator, _Allocator)
    -> multiset<__iter_value_type<_InputIterator>, less<__iter_value_type<_InputIterator>>, _Allocator>;

#    if _LIBCPP_STD_VER >= 23
template <ranges::input_range _Range, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value, void>>
multiset(from_range_t,
         _Range&&,
         _Allocator) -> multiset<ranges::range_value_t<_Range>, less<ranges::range_value_t<_Range>>, _Allocator>;
#    endif

template <class _Key, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value, void>>
multiset(initializer_list<_Key>, _Allocator) -> multiset<_Key, less<_Key>, _Allocator>;
#  endif

#  ifndef _LIBCPP_CXX03_LANG

template <class _Key, class _Compare, class _Allocator>
multiset<_Key, _Compare, _Allocator>::multiset(multiset&& __s, const allocator_type& __a)
    : __tree_(std::move(__s.__tree_), __a) {
  if (__a != __s.get_allocator()) {
    const_iterator __e = cend();
    while (!__s.empty())
      insert(__e, std::move(__s.__tree_.remove(__s.begin())->__value_));
  }
}

#  endif // _LIBCPP_CXX03_LANG

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator==(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {
  return __x.size() == __y.size() && std::equal(__x.begin(), __x.end(), __y.begin());
}

#  if _LIBCPP_STD_VER <= 17

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator<(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {
  return std::lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end());
}

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator!=(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {
  return !(__x == __y);
}

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator>(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {
  return __y < __x;
}

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator>=(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {
  return !(__x < __y);
}

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator<=(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {
  return !(__y < __x);
}

#  else // _LIBCPP_STD_VER <= 17

template <class _Key, class _Compare, class _Allocator>
_LIBCPP_HIDE_FROM_ABI __synth_three_way_result<_Key>
operator<=>(const multiset<_Key, _Compare, _Allocator>& __x, const multiset<_Key, _Compare, _Allocator>& __y) {
  return std::lexicographical_compare_three_way(__x.begin(), __x.end(), __y.begin(), __y.end(), __synth_three_way);
}

#  endif // _LIBCPP_STD_VER <= 17

template <class _Key, class _Compare, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI void
swap(multiset<_Key, _Compare, _Allocator>& __x, multiset<_Key, _Compare, _Allocator>& __y)
    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y))) {
  __x.swap(__y);
}

#  if _LIBCPP_STD_VER >= 20
template <class _Key, class _Compare, class _Allocator, class _Predicate>
inline _LIBCPP_HIDE_FROM_ABI typename multiset<_Key, _Compare, _Allocator>::size_type
erase_if(multiset<_Key, _Compare, _Allocator>& __c, _Predicate __pred) {
  return std::__libcpp_erase_if_container(__c, __pred);
}
#  endif

template <class _Key, class _Compare, class _Allocator>
struct __container_traits<multiset<_Key, _Compare, _Allocator> > {
  // http://eel.is/c++draft/associative.reqmts.except#2
  // For associative containers, if an exception is thrown by any operation from within
  // an insert or emplace function inserting a single element, the insertion has no effect.
  static _LIBCPP_CONSTEXPR const bool __emplacement_has_strong_exception_safety_guarantee = true;
};

_LIBCPP_END_NAMESPACE_STD

#  if _LIBCPP_STD_VER >= 17
_LIBCPP_BEGIN_NAMESPACE_STD
namespace pmr {
template <class _KeyT, class _CompareT = std::less<_KeyT>>
using set _LIBCPP_AVAILABILITY_PMR = std::set<_KeyT, _CompareT, polymorphic_allocator<_KeyT>>;

template <class _KeyT, class _CompareT = std::less<_KeyT>>
using multiset _LIBCPP_AVAILABILITY_PMR = std::multiset<_KeyT, _CompareT, polymorphic_allocator<_KeyT>>;
} // namespace pmr
_LIBCPP_END_NAMESPACE_STD
#  endif

_LIBCPP_POP_MACROS

#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
#    include <concepts>
#    include <cstdlib>
#    include <functional>
#    include <iterator>
#    include <stdexcept>
#    include <type_traits>
#  endif
#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)

#endif // _LIBCPP_SET