#include <iostream>
using namespace std;
long long f(long long n) {
	if (n == 1) return 1;
	return f(n - 1) * n;
}
int main() {
	long long n, ans;
	while (cin >> n) {
		ans = f(n);
		cout << ans << endl;
	}
}

/**************************************************************
	Problem: 1004
	User: lihean
	Language: C
	Result: Compile Error
****************************************************************/