Stuff

var
i, cnt: integer;
begin
  i:= 0;
  cnt := i;
  with Listbox1.Items do
    while Count > i do
    begin
      if IndexOf( strings[i] )<>i then
      begin
        Delete( i )
        inc(cnt)
      end
      else
        inc( i );
      ListBox1.ItemIndex := i;
  end;
  edit1.text := strtoint(cnt);
end;