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for (int c0 = 1; c0 < n - 1; c0 += 2) for (int c1 = c0 - 1; c1 <= c0; c1 += 1) S(c1); if (n >= 1) for (int c1 = n - 2; c1 < n; c1 += 1) if (2 * ((c1 + 2) / 2) >= n) S(c1);