题解

#include<bits/stdc++.h>
using namespace std;
int main() {
	int p,n[23] ={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,4,6,4,0,2};
	cin>>p;
	cout<<n[p-1];
	return 0;
}