#include<fstream>
#include <iostream>

using namespace std;

int N, phi[1000000];
long long nr_fractii;

int main()
{
    int i, j;
    ifstream f("fractii.in");
    ofstream g("fractii.out");

    f >> N;
    for(i = 1; i <= N; i++)
        phi[i] = i - 1;

    for(i = 1; i <= N; i++)
    {
        for(j = 2 * i ; j <= N; j = j + i)
            phi[j] -= phi[i];
    }

    nr_fractii = 0;
    for(i = 1; i <= N; i++)
       nr_fractii += phi[i];

    g << nr_fractii * 2 + 1;
    f.close();
    g.close();
    return 0;
}