#include <fstream>
using namespace std;

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

long long sol;
int n, F[1000010];
int main()
{
    ios_base::sync_with_stdio(0);
    fin.tie(NULL); fout.tie(NULL);

    fin >> n;
    for (int i = 2; i <= n; i++)
        F[i] = i - 1;

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

    fout << 2 * sol + 1;
    fin.close(); fout.close();
    return 0;
}