#include <fstream>

using namespace std;

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

const int NMAX = 1e6;
int n;
int p[NMAX];
long long ans;

int main() {
    in >> n;
    for (int i = 1; i <= n; ++i) {
            p[i] = i - 1;
    }
    for (int i = 2; i <= n; i += 1) {
        ans += p[i];
        for (int j = 2 * i; j <= n; j += i) {
            p[j] -= p[i];
        }
    }
    out << ans * 2 + 1 << "\n";
    return 0;
}