#include <fstream>

using namespace std;

const int NMAX = 1000000;

int v[1 + NMAX];

int main()
{
    ifstream in("fractii.in");
    ofstream out("fractii.out");

    int n;

    in >> n;

    for (int i = 2; i <= n; i++)
    {
        v[i] = i - 1;
    }

    long long sol = 0;

    for (int i = 2; i <= n; i++)
    {
        sol += v[i];

        for (int j = 2 * i; j <= n; j += i)
        {
            v[j] -= v[i];
        }
    }

    out << 2 * sol + 1 << '\n';

    return 0;
}