for (int c0 = 2; c0 <= min(100, -2 * n + 400); c0 += 2)
for (int c1 = 2 * n + c0; c1 <= 400; c1 += 2)
s0(c0, c1);
for (int c0 = 2; c0 <= min(100, -2 * n + 400); c0 += 2)
for (int c1 = 2 * n + c0; c1 <= 400; c1 += 2)
s0(c0, c1);