#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    int M;
    f >> M;
    int phi[499999];
    for (int i = 1; i <= M; ++i)
        phi[i] = i-1;
    for (int i = 2; i <= M; ++i)
        for (int j = 2*i; j <= M; j += i)
            phi[j] -= phi[i];
    int nr=0;
    for(int i=2; i<=M; i++)
            nr+=phi[i];
    nr=nr*2+1;
    g << nr;

}