#include <fstream>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int phi[1000005];

int main()
{
    long long n, sol=0, i, j;

    f>>n;

    for(i=2;i<=n;i++) phi[i]=i-1;

    for(i=2;i<=n;i++) {
    sol+=phi[i];

     for(j=2*i;j<=n;j+=i) phi[j]-=phi[i];

    }

    //dublam, deoarece fractiile se repeta, dar sunt invers + fractia 1/1

    g<<sol*2+1;

    f.close();
    g.close();
    return 0;
}