Need help with UNIX

The file /usr/share/dict/words contains a long list of words in the English language, one per line, arranged into alphabetical order. This file is normally used as the dictionary for spell checkers.

Suppose you were working a word puzzle and needed a 5-letter word beginning with an upper- or lower-case d, followed immediately by a lower-case vowel (including y), and ending with s.

The remaining letters could be any character that occurs in English words, including upper and lower-case alphabetics, numbers, hyphens, etc. (We will accept the file /usr/share/dict/words as the authority on what constitutes a valid English word and what characters can appear within one.)

What grep command would you use to list the words from /usr/share/dict/words that match this requirement?