#include <fstream>

using namespace std;
ifstream fin ("fractii.in");
ofstream fout ("functii.out");

int main()
{
    long long n,a=0;
    fin >> n;
    for (int p=1; p<=n; p++)
    {
        for (int q=1; q<=n; q++)
        {
            {if ((p%2==0)&&(q%2==0))
                {a=a;}
            else
                a=a+1;}
        }
    }
    fout << a;
    fin.close(); fout.close();
    return 0;
}