#include <iostream>

using namespace std;

int fact (int n)
{
	if (n == 0)
	return 1;
	
	return n * fact(n - 1);
}

int main()
{
	int n;
	int ans;
	
	cin >> n;
	
	
	cout << fact(n) << endl;
	
	return 0;
}