#include <bits/stdc++.h>

using namespace std;

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

int n;

int Phi(int n)
{
    int d, nr = n;
    for (d = 2; n > 1 && d * d <= n; d++)
    {
        if (n % d == 0)
        {
            nr = nr / d * (d - 1);
            while (n % d == 0) {n /= d;}
        }
    }

    if (n > 1) {nr = nr / n * (n - 1);}
    return nr;
}

int main(){

    f >> n;
    long long sum  = 0;
    for(int i = 1;i <= n;i++)
        sum += Phi(i);
    g << 2 * sum - 1;

}