#include <fstream>
using namespace std;

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

const int MAXN = 1000005;
int n;
int v[MAXN];

int main() {

    fin >> n;

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

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

    long long sol = 0;
    for (int i = 2; i <= n; ++i) {
        sol += v[i];
    }
    sol *= 2;
    sol++;

    fout << sol;

    fout.close();
    return 0;
}