#include<fstream>
#define DIM 1000002
using namespace std;

int N;
long long Sol;
int v[DIM];

int main()
    {
       ifstream f("fractii.in");
       ofstream g("fractii.out");
        f>>N;

        for (int i = 2; i <= N; i++)
            v[i] = i - 1;

        for (int i = 2; i <= N; i++)
            for (int j = 2; j * i <= N; j++)
                v[i * j] -= v[i];

        for (int i = 2; i <= N; i++)
            Sol += v[i];

        g<<Sol * 2 + 1;
    }