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

/**************************************************************
	Problem: 1004
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/