#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    int N, fr=0, i, j, ev;
    f>>N;
    for(i=1; i<=N; i++)
    {
        ev=1;
        for(j=1; j<=N; j++)
        {
            if(i>1&&j>1)
            {
            if(i%2!=0&&j%2!=0)
                ev=0;
            if(i%2==0&&j%2==0)
                ev=0;
            }

        if(ev==1)
        {
            fr++;
        }
        if(ev==0)
            ev=1;
        }

    }
    g<<fr;
    return 0;
}