#include <fstream>
using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int euler[1000000], i, j, N, sol = 0;

int main()
{
    fin >> N;

    for(i = 1; i <= N; i++)
        euler[i] = i - 1;

    for(i = 2; i <= N; i++)
    {
        sol = sol + euler[i];
        for(j = i + i; j <= N; j += i)
            euler[j] = euler[j] - euler[i];
    }

    fout << sol * 2 + 1;

    return 0;
}