#include <iostream>
#include <fstream>
#include <vector>

using namespace std;
int phi[1000000];

int main()
{
    ifstream in("fractii.in");
    ofstream out("fractii.out");
    int n, total;
    in>>n;
    for (int i = 1; i <= n; i++)
            phi[i] = i-1;
    for (int i = 2; i <= n; i++)
        for (int j = 2*i; j <= n; j += i)
            phi[j] -= phi[i];

    total = n;
    for(int i = 2; i <= n; i++)
    {
        if(phi[i] == i-1)
            total += n-1;
        else
            total += (n-1)-phi[i];
    }
    out << total;






    return 0;
}