// Recursive factorial function
#include <iostream>
using namespace std;

int fact (int n){
  if (n > 1)
    return n * fact(n-1);
  else
    return 1;
}

int main ()
{
  int number;

  cout << "Input a number: ";
  cin >> number;
  cout << number << "! = " << fact(number);

  return 0;
}