#include <iostream>
#include <math.h>

int main()
{
	long int n;
	long int product;
	long int i;

	cout << "Enter an integer: ";
	cin >> n;
	
	product = 1;
	for (i = 1; i <= n; ++i)
	{
		//cout << " DEBUG: i,n,product " << i << " " << n << " " << product << endl;
		product *= i; // same as product = product * i;
	}
	
	cout << n << " factorial is " << product << endl;
}