#include <iostream>
using namespace std;

int fakultaet(int i) {
	if (i<=1) return 1;
	else return i*fakultaet(i-1);
}

int main() 
{
	int x,f;
	cout << "x = ";
	cin >> x;
	f = fakultaet(x);
	cout << "x! = " << f << endl;
	return 0;
}