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:
['6463', '871', '5781', '283', '9653', 'f', '9661', '3365', '2889', '5499']
answer:
f


question:
['w', '1367', '5389', '9515']
answer:
w


question:
['z', 'i', '3657', 'p', '6985', '2293', '8113', '4129', '8753', 'd', 'd', '8273', 's', '9909', '4721', '7703', '3861', 'f', '7343', 's']
answer:

d, f, i, p, s, z