#include <iostream>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <functional>

using namespace std;

int main()
{
	unsigned long n, res = 1;

	cin >> n;

	for ( int i = 1; i <= n; i++ )
	{
		res *= i;
	}

	cout << res << endl;

	return 0;
}