#include <iostream>
#include <fstream>
using namespace std;
long long nr;
long a[1000001], n, i, j;
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f >> n;
    for (i = 1; i <= n; i++)
        a[i] = i - 1;
    for (i = 2; i <= n; i++) {
        for (j = 2 * i; j <= n; j += i)
            a[j] -= a[i];
        nr += a[i];
    }
    g << 2 * nr + 1 << endl;
    f.close ();
    g.close ();
    return 0;
}