1for (int c0 = 0; c0 <= M; c0 += 1) {
2  for (int c1 = 0; c1 <= min(N, c0); c1 += 1) {
3    S1(c0, c1);
4    S2(c0, c1);
5  }
6  for (int c1 = max(0, N + 1); c1 <= c0; c1 += 1)
7    S1(c0, c1);
8  for (int c1 = c0 + 1; c1 <= N; c1 += 1)
9    S2(c0, c1);
10}
11