#include<bits/stdc++.h>
using namespace std;
int main(){
    long long n,d=1;
    cin>>n;
    for(int i=1;i<=n;i++){
        d=d*i;
    }
    cout<<d;
}
/**************************************************************
	Problem: 1285
	User: wangyiyang
	Language: C++
	Result: Wrong Answer
****************************************************************/