#include <iostream>
#include <fstream>

using namespace std;

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

long N;
long a[100000];

int main()
 {
    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;
}