#include <iostream>
#include <fstream>
#include <cmath>

bool prim(int num)
{
    for(int d = 2; d <= sqrt(num); ++d){
        if(num % d == 0){
            return false;
        }
    }
    return true;
}

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

    unsigned long int N;
    in >> N;

    unsigned long int num_total_fractii = N * N - (N - 1);
    unsigned long int num_fractii_reductibile = 0;
    for(int i = 2; i <= N; ++i){

        if(prim(i) == true){

            int x = N / i;
            num_fractii_reductibile += x * x - x;
        }
    }

    out << num_total_fractii - num_fractii_reductibile;
    return 0;
}