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:
['n', '9571', '2983', '7597', 'v', 'y', '1993', '1403', '8309', '7043', 'c', '7329', 'p', '4479', 'p']
answer:
c, n, p, v, y


question:
['6143', '9073', 'h', '1459', 'q', '5799', '6555', '525', '7921', '5041', '3273', '383', 'd', '9075']
answer:
d, h, q


question:
['8347', '4217', '2245', '8489', '2737', '1245', '3319', '7017', '1527', 'x', 'n', '9033', 'k', 'm', '4605', 'r', '6805', '6471']
answer:

k, m, n, r, x