#include <stdio.h>
int multiply (int n){
if(n == 0 ) return 1;
else return multiply(n-1)*n;
}
int main () {
printf("0! = %d\n", multiply(0));
printf("1! = %d\n", multiply(1));
printf("2! = %d\n", multiply(2));
printf("3! = %d\n", multiply(3));
printf("4! = %d\n", multiply(4));
return 0;
}