recursive factorial

#include <stdio.h>

int
ff (int nb)
{
  if (nb == 0)
    {
      return 1;
    }
  else if ((nb > 12) || (nb < 0))
    {
      return 0;
    }
  else
  {
    return (nb * ff (nb - 1));
  }
}





main ()
{
  int a = 5;
  ff (a);
  printf ("%d", ff (a));
}