#include <cstdio>

#include <fstream>

using namespace std;

int main()  {
    ifstream fin("fractii.in", ios::in);
    ofstream fout("fractii.out", ios::out);
    long long N, counter = 0, p[1000000];
    fin >> N;
    for(int i = 2 ; i <= N ; i++)
        p[i] = i - 1;
    for(int i = 2 ; i <= n ; i++)    {
        counter += p[i];
        for(int j = 2 * i ; j < =n ; j = j + i)
            p[j] -= p[i];
    }
    fout << 2 * counter + 1;
    fin.close();
    fout.close();
    return 0;
}