#include <fstream>
#define intrare "fractii.in"
#define iesire "fractii.out"

using namespace std;

ifstream in(intrare);
ofstream out(iesire);

int n, phi[10000005];

void Solve()
{
    int N;
    in >> 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];
    long long k = 0;
    for (int i = 1; i <= N; ++i)
        k += phi[i];
    k *= 2;
    k++;
    out << k;
}

int main()
{
    Solve();
    return 0;
}