#include <iostream>

using namespace std;

int factorial(int n)
{
  //if (n  < 0) return -1;
  //if (n == 0) return  1;
  if (n == 1) return  1;
  
  return n*factorial(n-1);
}


int main()
{

  for (int i=1; i<=20; i++) {
    cout <<  i << "\t" << factorial( i) << endl;
  }
  
  cout << -2 << "\t" << factorial(-2) << endl;
  //cout << -268435446 << "\t" << factorial(-268435446) << endl;

}