for (int c0 = 1; c0 <= 8; c0 += 1) {
  if (c0 >= 2) {
    if (c0 <= 6)
      for (int c1 = 0; c1 < c0 - 1; c1 += 1)
        s1(c0, c1);
    for (int c1 = c0 - 1; c1 <= 4; c1 += 1) {
      s1(c0, c1);
      s0(c0, c1);
    }
    for (int c1 = max(5, c0 - 1); c1 <= 7; c1 += 1)
      s0(c0, c1);
  } else
    for (int c1 = 0; c1 <= 7; c1 += 1)
      s0(1, c1);
}