#include <iostream>

using namespace std;

unsigned long long factorial(int n) {
	if (n<0)
		return 0;
	if (n==0)
		return 1;
	return n*factorial(n-1);
}

int main(void) {
	int n;
	cin >> n;
	cout<<"factorial("<<n<<")="<<factorial(n);
	system("pause");
}