var     s:int64;
        i,j,n:longint;
        f:text;
        a:array [0..1000000] of int64;

begin
  assign(f,'fractii.in');
  reset(f);
  readln(f,n);
  close(f);

  for i:=1 to n do
    a[i]:=i-1;
  for i:=2 to n do
    begin
      inc(s,a[i]);
      j:=i*2;
      while j<=n do
        begin
          dec(a[j],a[i]);
          inc(j,i);
        end;
    end;
  s:=s*2+1;
  assign(f,'fractii.out');
  rewrite(f);
  writeln(f,s);
  close(f);
end.