#include <iostream>
using namespace std;

int factorial(int n)
{
  int f;
  if (n < 2) // detecting a base case
    f = 1;
  else
    f = n * factorial(n - 1);
  return f;
} // factorial

int main()
{
  int n;
  cout << "Enter n: ";
  cin >> n;
  cin.ignore(1000, 10);

  cout << factorial(n) << endl;
} // main