#include <iostream>
using namespace std;
int main()
{
	int n,x=1,s=1;
	cin >> n;
	while(x<=n)
	{
		
		s = s * x;
		x++;
	}
	cout << s;
}
/**************************************************************
	Problem: 1004
	User: xiaomingze
	Language: C++
	Result: Accepted
	Time:20 ms
	Memory:2072 kb
****************************************************************/