{

  S3(1, 0);

  for (int c2 = 2; c2 <= M; c2 += 1)

    S1(1, 1, c2);

  for (int c0 = 2; c0 <= M; c0 += 1) {

    S4(c0, 0);

    for (int c2 = c0 + 1; c2 <= M; c2 += 1)

      S2(c0, 1, c2);

  }

}