#include <fstream>
using namespace std;

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

long long int phi[1000008];
long long int total;

int main()
{
    int N;
    fin>>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];
    for(int i = 0; i <= N; i++){
        total += phi[i]*2;
    }
    fout<<total+1;
}