#include <iostream>
#include <stdio.h>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;


int main(void){

	int n;
	cin >> n;

	unsigned long long int ans = 1;

	for( int i = 1; i <= n; i++ )
		ans *= i;

	cout << ans << endl;

    return 0;
}