(1.3)

Otherwise, (ranges::end(E) - ranges::begin(E)) if it is a valid expression and the types I and S of ranges::begin(E) and ranges::end(E) model SizedSentinel<S, I> ([iterator.concept.sizedsentinel]) and ForwardIterator<I>.

However, E is evaluated only once.

I don't remember similar wording not including "respectively", so I'd guess this wording allows the interpretation of S denoting ranges::begin(E) and I denoting ranges::end(E).