#include<iostream>
#include<fstream>
using namespace std;
int a[1000005];
int n,i,j,h;
long long nr;

int main() {
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f>>n;
    nr=1;
    for (i=2; i<=n; i++)
        a[i]=i-1;
    for (i=2; i<=n; i++)
    {
        nr=nr+2*a[i];
        h= n / i;
        for (j=2; j<=h; j++)
            a[i*j]=a[i*j] - a[i];
    }
    g<<nr;
    f.close();
    g.close();
    return 0;
}