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