Among the substrings of a lowercase string whose first letter is a vowel and whose last letter is a consonant, find the alphabetically smallest and the alphabetically largest.

Given a string s of lowercase letters, between 3 and 500,000 characters long, consider every substring whose first letter is a vowel (a, e, i, o, u) and whose last letter is a consonant (any other letter). Output two results: the one that comes first in dictionary order, then the one that comes last. Example: for 'ubeat' the candidates are 'ub', 'ubeat', 'eat' and 'at', so the answers are 'at' and then 'ubeat'.