1for (int c1 = 1; c1 <= M; c1 += 1)
2  S1(0, c1);
3for (int c0 = 1; c0 <= N; c0 += 1)
4  for (int c1 = 1; c1 <= M; c1 += 1)
5    S2(c0, c1);
6