#include <fstream>
#define maximum 1000001
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

int vector[maximum];

void citire(int &n)
{
    fin>>n;
}

long long calcul(int n)
{
    long long fr = 0;

    for ( int i = 2; i <= n; i++)
    {
        vector[i] = i - 1;
    }
    for ( int i = 2; i <= n; i++)
    {
        for ( int j = 2*i; j <= n; j+=i)
        {
            vector[j] -= vector[i];
        }
        fr += vector[i];
    }
    return fr;
}

int main()
{
    int n;
    citire(n);
    long long nr = calcul(n);
    nr *= 2;
    nr += 1;
    fout << nr;
    return 0;
}