#include<iostream>
#include <iomanip>
using namespace std;
int main() {
	int n;
	cout << "n = ";
	cin >> n;
	if (n<0) {
		cout << "Error: n has to be a positive integer or zero!";
	} else {
		double f = 1;
		for (int i=2; i<n+1; i++) {
			f *= i;
		}
		cout << n << "! = " << fixed << setprecision(0) << f;
	}
	return 0;
}