#include <fstream>

int cmmdc(int a, int b) {
    return b == 0 ? a : cmmdc(b, a % b);
}

int main() {
    std::ifstream f("fractii.in");
    std::ofstream g("fractii.out");
    int n;
    f >> n;
    int v[1000000] = { 0 };
    for (int i = 2; 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 nr = 0;
    for (int i = 2; i <= n; i++) {
        nr += v[i];
    }
    g << nr * 2 + 1;
}