#include<bits/stdc++.h>
using namespace std;
int main(){
	int a=1,c=1,b;
	cin>>b;
	while(a<=b){
		c=a*c;
		a++;
	}
	cout<<c;
}

/**************************************************************
	Problem: 1004
	User: toughuatao1
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/