#include <iostream>

using namespace std;

size_t Factorial(size_t);

int main() {
   size_t i;

   for(i =0; i < 15; ++ i) {
      cout << i << "! = " << Factorial(i) << endl;
   }

   return 0;
}

size_t Factorial(size_t n){
    if (n == 1 or n == 0) {
       return 1;
    } else {
       return n * Factorial(n-1);
    }
}