#include <bits/stdc++.h>
using namespace std;
int main(){
	int n=1,s=1,h=1;
	cin>>n; 
	while(s<=n) {
		h=s*h;
		s++; 
	}
	cout<<h; 
	}










 
/**************************************************************
	Problem: 1004
	User: zhuangwenya
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/