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

/**************************************************************
	Problem: 1004
	User: zhengzihao3
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/