instruction:
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:
['c', 'e', '6509', '1295', 'u', '5445', '1731', '3049']
answer:
c, e, u


question:
['s', 'w', '8949', '4025']
answer:
s, w


question:
['r', '9641', 'n', '3497', '9849', '2497', 'd', '1163', '9705', '5039', '4773', '445', 's', '2563', 'g', '527', '5743', 'w', '239', 'p', '8489', 'h', 'g', 'n', 's', 't', 'd', 'y', 'o', 'v', '9431', 'n', '9339', '6181', 's', 'n', 'g', '5431', '105']
answer:

d, g, h, n, o, p, r, s, t, v, w, y