#include <stdio.h>

int getnum(void);
int factorial(int n);

int main()
{
   int value;

   printf("Enter 0 to exit.\n");

   value = getnum();

   while (value != 0)
   {
      printf("Factorial: %d\n", factorial(value));
      value = getnum();
   }

   return 0;
}


int getnum(void)
{
   int num;

   printf("Number: ");
   scanf("%d", &num);
   return num;
}


int factorial(int n)
{
   if (n <= 1)
      return 1;

   return n * factorial(n - 1);
}