#include <stdio.h>

double factorial (int i)
{
   double f = 1.0, g;
   
   if (i > 0) {
      g = factorial(i-1) * i;
      f = g;
   }
   return f; 
}

int main (int argc,char *argv[]) 
{
   int n;
   double f;
   
   if (argc == 2) 
     {	
	n = atoi(argv[1]);
	f = factorial(n);
	printf("Factorial of %d is %.0lf\n",n,f);
     }
   return 0;
}