In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
--------
Question: ['1429', '7273']

Answer: -1


Question: ['p', '5229', '7521', 'y', 'n', 'u', 'c', '4047', '781', 'a', '4707', '7149', 'j', 'm', 't', '515', '7691', 'h', '4879', 'j', '6593', 'n', 'p', '2949', '1343', 'y', '2629', 'p', 'b', 'b', '2861', 'a']

Answer: a, b, c, h, j, m, n, p, t, u, y


Question: ['q', 'e', '1081', '5263', 'a', '5869', '949', 'm', 'x', 'n', 'w', '7643', '1225', '7381', 'p', '5567', 'z', 'r', '3523', 'b', 'z', 'u', '5399', '6641', 'a', '8659', '7423']

Answer:
a, b, e, m, n, p, q, r, u, w, x, z