#include<bits/stdc++.h>
using namespace std;
int n,ans;
int main(){
	
	cin>>n;
	for(int i=1;i<=n;i++) ans*=i;
	cout<<ans;
	return 0;
} 

/**************************************************************
	Problem: 1004
	User: linzihao
	Language: C
	Result: Compile Error
****************************************************************/