#include <fstream>
#define inFile "fractii.in"
#define outFile "fractii.out"
#define maximum 1000001
using namespace std;

ifstream in(inFile);
ofstream out(outFile);

int vector[maximum];

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

long long calcul(int n)
{
    long long Fractions = 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];
        }
        Fractions += vector[i];
    }
    return Fractions;
}

int main()
{
    int n;
    citire(n);
    long long variante = calcul(n);
    variante *= 2;
    variante++;
    out<<variante;
    return 0;
}