//打表找规律
#include <iostream>

using namespace std;

int n;

int main()
{
    cin>>n;
    if(n==1) cout<<0;
    else if(n==2) cout<<2;
    else if(n==3) cout<<4;
    else 
    {
        if(n%2==0) cout<<4;
        else cout<<6;
    }
}