#include <iostream>
#include<fstream>
#define Nmax 1000001
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int sol[Nmax];
int main()
{
    int N;
    f >> N;
    for(int i = 2; i <= N; i++)
        sol[i] = i - 1;
    for(int i = 2; i <= N; i++)
        for(int j = 2 * i; j <= N; j += i)
            sol[j] -= sol[i];
    long long rez = 0;
    for(int i = 2; i <= N; i++)
        rez += sol[i];
    rez *= 2;
    rez += 1;
    g << rez;
    return 0;
}