#include <fstream>
using namespace std;

ifstream f ("fractii.in");
ofstream g ("fractii.out");

int v[1000001];

int main ()
{
    int i, j, n;
    long long nr = 0;
    f>>n;


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


    for (i=2; i<=n; i++)
    {
        nr += v[i];
        for (j=2*i; j<=n; j+=i)
            v[j] -= v[i];
    }

    g<<2*nr+1;
}