void square(int x, int y, int top) {
  if(top == 0) {
    if(x == 0 && y == 0) {
      printf("%i\n", counter);
      counter+=2;
      return;
    }
    if(x > 0)
      square(x-1, y, 0);

    if(y > 0)
      square(x, y-1, 0);
  } else {
    square(x, y-1, 0);
  }

}

int main(void) {
 square(20, 20, 1);
 printf("%i\n", counter);
}