#include <bits/stdc++.h>
using namespace std;
ifstream f("instabook.in");
ofstream g("instabook.out");
long long n, i, j, a, k, nmax, s, phi[1000002], vizitat[1000002];


int main()
{
    f >> n;
    for(i = 1; i <= n; i++)
        phi[i] = i - 1;
    for(i = 2; i <= n; i++)
        for(j = 2 * i; j <= n; j += i)
            phi[j] -= phi[i];
    for(i = 1; i <= n; i++)
        s += phi[i];
    g << (s * 2 + 1);
    return 0;
}