if (n >= 2)

  for (int c0 = 1; c0 <= n; c0 += 1) {

    for (int c1 = 2; c1 <= c0; c1 += 1)

      for (int c3 = 1; c3 < c1; c3 += 1)

        s1(c3, c1, c0);

    for (int c1 = c0 + 1; c1 <= n; c1 += 1) {

      for (int c3 = 1; c3 < c0; c3 += 1)

        s1(c3, c1, c0);

      s0(c0, c1);

    }

  }