hu

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,a,b;
    {
       scanf("%d",&n);
       if(n%3!=0)
        printf("\n %d \n",((n-1)/3)*8+(n%3)+1);
       else printf("\n %d \n",((n-1)/3)*8+4);
    }
    return 0;
}