#include <iostream>
using namespace std;

int main(){
	int i,s = 1,n;
	cin>>n;
	for(i = 1;i <= n;i++){
		s = s * i;
	}
	
	cout<<s<<endl;
	return 0;
}
/**************************************************************
	Problem: 1004
	User: admin
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/