#include <fstream>
using namespace std;
int main()
{
  int i, j, N;
  long long count = 0;
  
  ifstream in("fractii.in");
  ofstream out("fractii.out");

   in>>N;
   in.close();
   long long V[N+1];
   for(i=1;i<=N;i++) V[i] = i-1;
   for(i=2;i<=N;i++)
   {
       for(j=i+i;j<=N;j+=i)
          V[j]-=V[i];
       count+=V[i];
    }

  count= count*2+1;
  out<<count<<"\n";
  out.close();
  return 0;
}