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


}
/**************************************************************
	Problem: 1004
	User: zhangyilei
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/