#include <iostream>
#include <fstream>

using namespace std;

ifstream f ("fractii.in");
ofstream g ("fractii.out");

const int NMAX = 1000000;
int n;
long long sol, v[NMAX];

void rezolva () {
    for (int i = 2; i <= n; i++) {
        v[i] += i - 1;
        for (int j = i + i; j <= n; j+= i) v[j] -= v[i];
        sol += v[i];
    }
    sol = sol * 2 + 1;
    g << sol << '\n';
}

int main () {
    f >> n;
    rezolva ();
    return 0;
}