#include<iostream>
#include<cmath>
#include<algorithm>
#include<string>
#include<map>
using namespace std;
long long sum(int n) {
	if (n == 1) {
		return 1;
	}
	return n * sum(n - 1);
}
int main() {
	int n;
	while (cin >> n) {
		cout << sum(n) << endl;
	}
	return 0;
}