XML : Extract in XQuery the first element of a list

I want to extract the first element form the list $res/Name. In my solution I obtain all the list and not only the first element, here is what I wrote.

  for $res in /Restaurants/Restaurant  let $n := count($res/Dish)  order by $n descending  return ($res/Name)[1]    

You can see here the XML and the result: http://www.xpathtester.com/xquery/7992b12910492f493273835e828dc386

Where is the problem?