for (int c0 = 2; c0 <= 10; c0 += 3) {
  S1(c0, (c0 + 1) / 3, (c0 + 1) / 3, 2, (c0 - 2) / 3);
  S2(c0, (c0 + 1) / 3, (c0 + 1) / 3, 2, (c0 - 2) / 3);
  S3(c0, (c0 + 1) / 3, (c0 + 1) / 3, 2, (c0 - 2) / 3);
}