#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

int phi[1000000];

int main()
{
    int n, i, j, r;
    while(fin >> n)
    {
        r = 0;

        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++)
            r += phi[i];

        fout << 2 * r + 1 << '\n';
    }



}