{
  for (int c0 = 0; c0 <= 8; c0 += 1) {
    for (int c1 = 0; c1 <= -c0 + 8; c1 += 1)
      for (int c2 = 10 * c0; c2 <= 10 * c0 + 9; c2 += 1)
        for (int c3 = 10 * c1; c3 <= 10 * c1 + 9; c3 += 1)
          A(c2, c3);
    for (int c1 = -c0 + 9; c1 <= -c0 + 10; c1 += 1)
      for (int c2 = 10 * c0; c2 <= min(10 * c0 + 9, -10 * c1 + 100); c2 += 1)
        for (int c3 = 10 * c1; c3 <= min(10 * c1 + 9, -c2 + 100); c3 += 1)
          A(c2, c3);
  }
  for (int c0 = 9; c0 <= 10; c0 += 1)
    for (int c1 = 0; c1 <= -c0 + 10; c1 += 1)
      for (int c2 = 10 * c0; c2 <= min(10 * c0 + 9, -10 * c1 + 100); c2 += 1)
        for (int c3 = 10 * c1; c3 <= min(10 * c1 + 9, -c2 + 100); c3 += 1)
          A(c2, c3);
}