1 for (int c0 = 1; c0 <= 4; c0 += 1)
2   for (int c1 = 5; c1 < M - 9; c1 += 1)
3     S1(c0, c1);
4 for (int c0 = 5; c0 < M - 9; c0 += 1) {
5   for (int c1 = -c0 + 1; c1 <= 4; c1 += 1)
6     S2(c0 + c1, c0);
7   for (int c1 = 5; c1 <= min(M - 10, M - c0); c1 += 1) {
8     S2(c0 + c1, c0);
9     S1(c0, c1);
10   }
11   for (int c1 = M - c0 + 1; c1 < M - 9; c1 += 1)
12     S1(c0, c1);
13   for (int c1 = M - 9; c1 <= M - c0; c1 += 1)
14     S2(c0 + c1, c0);
15 }
16 for (int c0 = M - 9; c0 <= M; c0 += 1)
17   for (int c1 = 5; c1 < M - 9; c1 += 1)
18     S1(c0, c1);
19