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

}

/**************************************************************
	Problem: 1004
	User: houshanglin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/