// Paragontiko anadromiko
#include <iostream> 
#include <cstdlib>
using namespace std;

long int factorial(int n)
{
 if (n==0) return 1;
 else return n*factorial(n-1);
}

int main(int argc, char *argv[])
{ int n;
  long int f;
  cout<<"Dose n <=12: ";
  cin>>n;
  f=factorial(n);
  cout<<n<<"! = "<<f<<endl;
  system("PAUSE");
  return 0;
}