One way would be to create a constructed list with instructions like this:
"RankingQ" being the name of your ranking question, naturally.
That will give us an ordered list of the ranked items. Now we can pull off the first or last items from the list with scripts like these:
[% ListLabel(list1, 1) %]
[% ListLabel(list1, ListLength(list1)) %]
"list1" being our new constructed list.