#include<stdio.h>

int factorial(int n);


void main()
{
  int n, f;

  printf("\n Enter n: ");
  scanf("%d", &n);

  f=factorial(n);

  printf("\n %d!=%d\n", n, f );

}


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

}