#include <fstream>
#define DIM 1000005

using namespace std;

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

int N, v[DIM];
long long Sol;
int main(){

    fin >> N;

    for(int i = 2; i <= N; i ++)
        v[i] = i - 1;


    for(int i = 2; i <= N; i ++){

        for(int j = 2 * i; j <= N; j += i)
                v[j] -= v[i];

        Sol += v[i];
    }

    Sol = 2 * Sol + 1;

    fout << Sol << "\n";

    fin.close();
    fout.close();

    return 0;

}