#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: 1003
	User: xuezihong1
	Language: C++
	Result: Wrong Answer
****************************************************************/