--     Author: Rodney Shaghoulian
--     Github: github.com/RodneyShag
-- HackerRank: hackerrank.com/RodneyShag

SELECT DISTINCT CITY FROM STATION
WHERE CITY REGEXP '^[aeiou]';

--  Pattern   | What the pattern matches
---------------------------------------
--    ^       |  Beginning of string
--  [...]     |  Any character listed between the square brackets

-- Useful Reference: https://www.tutorialspoint.com/mysql/mysql-regexps.htm