#include<bits/stdc++.h>
using namespace std;
int main(){
	int i=1,z,s=1;
	cin>>z;
	while(i<=z){
		s=s*i;
		i=i+1;
	}cout<<s;
}
/**************************************************************
	Problem: 1004
	User: sucongyi
	Language: C++
	Result: Accepted
	Time:19 ms
	Memory:2072 kb
****************************************************************/