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

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