Untitled

#include <iostream>

using namespace std;

int main()
{
	int A; 
	cin >> A;

	long long res = 1;
	for (int i = 1; i <= A; i++) {
		if (A == 0) {
			res = 1;
			break;
		}
		else if (A == 1) {
			res = 1;
			break;
		}
		res *= i;
	}
	cout << res;
}