#include <bits/stdc++.h>
using namespace std;

ifstream fin ("fractii.in");
ofstream fout("fractii.out");

int phi(int n)
{
    int nr = n;
    for (int d = 2; d * d <= n; d ++)
        if (n % d == 0)
        {
            nr = nr * (d - 1) / d;
            while (n % d == 0)
                n /= d;
        }
    return n == 1 ? nr : nr * (n - 1) / n;
}

int main()
{
    int n, nr = 1;
    fin >> n;

    for (int i = 2; i <= n; i ++)
        nr += 2 * phi(i);

    fout << nr;

    fin.close();
    fout.close();

    return 0;
}