#include <iostream>
#include <fstream>
#include <climits>

int phi[1000001];
int main()
{
    std::ifstream in("fractii.in");
    std::ofstream out("fractii.out");

    unsigned long int N;
    in >> N;

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

    int num = 0;
    for(int i = 1; i <= N; ++i){
        num += phi[i];
        for(int j = 2 * i; j <= N; j += i){
            phi[j] -= phi[i];
        }
    }

    out << num * 2 - 1;
    return 0;
}