#include <fstream>
using namespace std;

const int NMAX = 1000010;

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

int n;
long long int sol;
int euler[NMAX];

int main()
{
    f >> n;
    for (int i = 2; i <= n; i++)
        euler[i] = i - 1;

    for (int i = 2; i <= n; i++)
    {
        sol += euler[i];
        for (int j = 2 * i; j <= n; j += i)
            euler[j] -= euler[i];
    }
    g << 2 * sol + 1 << endl;
    return 0;
}