#include <iostream>
#include <fstream>


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

    int N;
    in >> N;
    std::cout << N;
    ///Indicatorul lui Euler

    //Initializare
    int phi[N + 1] = {};
    for(int i = 1; i <= N; ++i){
        phi[i] = i - 1;
    }

    //Procedura enigmatica prin care se afla phi de toate numerele de la 1 la n
    int answer = 0;
    for(int i = 2; i <= N; ++i){
        int j = 2 * i;
        for(; j <= N; j += i){
            phi[j] -= phi[i];
        }
        answer += phi[i];
    }

    out << 2 * answer + 1;
    return 0;
}