#include <bits/stdc++.h>

using namespace std;

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

const int dim = 1e6+1;
int phi[dim];

int main()
{
    phi[1] = 1;
    for (int i=2; i<dim; i++)
        phi[i] = i-1;

    for (int i=2; i<dim; i++)
    {
        for (int j=i+i; j<dim; j+=i)
            phi[j] -= phi[i];
    }

    long long ans = 0;

    int n;
    in >> n;

    for (int i=1; i<=n; i++)
        ans += phi[i];
    out << ans*2-1;

    return 0;
}