for (int c0 = -99; c0 <= 100; c0 += 1) {
  if (c0 >= 1)
    S2(c0, 1);
  for (int c1 = max(1, -c0 + 1); c1 <= min(99, -c0 + 100); c1 += 1) {
    S1(c0 + c1, c1);
    S2(c0 + c1, c1 + 1);
  }
  if (c0 <= 0)
    S1(c0 + 100, 100);
}