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

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