program fractii;
var n,i,j:longint;
    nr:int64;
    v:array[1..1000005] of longint;
    f,g:Text;
 begin
  assign(f,'fractii.in');
  assign(g,'fractii.out');
  reset(f);
  rewrite(g);
  readln(f,n);
  close(f);
  for i:=1 to n do
   v[i]:=i-1;
  for i:=2 to n do
   begin
    j:=2*i;
     while j<=n do
      begin
       v[j]:=v[j]-v[i];
       j:=j+i;
      end;
   end;
  for i:=2 to n do
   nr:=nr+v[i];
  writeln(g,nr*2+1);
  close(g);
 end.