#include<fstream>

using namespace std;

int main()
{ ifstream f("fractii.in");
  ofstream g("fractii.out");
  int n,i,numar,j;
  char v[1000005];
  f>>n;
  for(i=1;i<=n;i++)
  v[i]=i-1;;
  for(i=2;i<=n;i++)
  { numar=numar+v[i];
   for(j=i+i;j<=n;j=j+i)
    v[j]-=v[i];
   }
   numar=numar*2+1;
  g<<numar;
  f.close();
  g.close();
  return 0;
}