#include <iostream>
#include <fstream>

using namespace std;

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

long long N;
long long a[1000001];

int main()
 {
    long long k=0;
    f >> N;
    for (int i = 2; i <= N; i++)
      a[i] =i-1;

 for (int i = 2; i <= N / 2; i++)
        for (int j = 2 * i; j <= N; j += i)
          a[j]=a[j]-a[i];

    for (int i = 2; i <= N; i++)
       k=k+a[i];
    g<< k*2+1;
return 0;
}