#include <iostream>
#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");

int Euler[1000001];


int main()
{
    int N;
    long long sum = 0;
    in >> N;
    for(int i = 2; i <= N; i++)
        Euler[i] = i - 1;
    for(int i = 2; i <= N; i++)
    {
        for(int j = 2 * i; j <= N; j+=i)
            Euler[j] -= Euler[i];
        sum += Euler[i];
    }
    out << 2 * sum + 1;
    return 0;
}