for (int c0 = 1; c0 <= 9; c0 += 1) {

  if (c0 % 2 == 0) {

    for (int c1 = 1; c1 <= 9; c1 += 1) {

      s0(c1, c0);

      s1(c1, c0);

    }

  } else

    for (int c1 = 1; c1 <= 9; c1 += 1)

      s0(c1, c0);

}