#include<bits/stdc++.h>
using namespace std;
int end = 1;
int factorial(int n)
{
	if(n >= 1)
	{
		end *= n;
		factorial(n-1);
	}
	else
	{
		return end;
	}
}
int main()
{
	int n;
	cin >> n;
	cout << factorial(n) << endl ;
	
	
	return 0;
 }