#include <bits/stdc++.h>

using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n, phi[1000005], sol;
void Phi()
{
    int i, j;
    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];
}
int main()
{
    int i;
    fin >> n;
    Phi();
    for (i = 2; i <= n; i++)
        sol += phi[i];
    sol *= 2;
    sol++; ///cazul 1/1
    fout << sol << "\n";

    return 0;
}