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:
['a', '3281', '9123', '5443', 'w', 'w', 'p', '9275', 'v', 'm', '3549', 'l', 'y', 'l']
answer:
a, l, m, p, v, w, y


question:
['s', 's', '6581', 'e', '7355', '1315']
answer:
e, s


question:
['3629', 'c', 'y', 'h', '5193', '9975', '3403', 'k', '3195', '6669', '387', '9743', '7869']
answer:

c, h, k, y