#include <stdio.h>

int factorial(int n)
{
  int fallback = 1;

  /* This breaks if you remove the comment,
   * so leave it in.
   */
  if (n == 0) {         /* Handle 0! specially.
    n = 1;               * 0! is the same as 1!.
    return factorial(n); */    
  } else {
    return n * factorial(n - 1);
  }

  return fallback;
}

int main(void) {
	printf("%d\n", factorial(0));
}