#include<bits/stdc++.h>
using namespace std;
int main(){
	int i=1,j=1,n;
	cin>>n;
	while(i<=n){
		j=i*j;
		i++;
	}
	cout<<j;
}
/**************************************************************
	Problem: 1004
	User: hongjiaming
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/