#include <iostream>
#include <fstream>

using namespace std;

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

const int nMax = 1000005;

int n;
int v[nMax];
long long rasp = 0;

void citire()
{
    in >> n;
}

void rezolvare()
{
    for(int i = 1; i <= n; ++i)
        v[i] = i;
    for(int i = 1; i <= n; ++i)
    {
        for(int k = 2; k * i <= n; ++k)
            v[k * i] -= v[i];
    }
    for(int i = 1; i <= n; ++i)
    {
        rasp += (1LL * v[i] * 2);
    }
    out << rasp - 1 << "\n"; //-1 pt ca am luat 1/1 de 2 ori cand am inmultit
}

int main()
{
    citire();
    rezolvare();
    return 0;
}