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:
['g', '4165', 'n', 'w', 'n', 'e']
answer:
e, g, n, w


question:
['w', '491', 'x', 'u', 'z', 'q', '5411', '7629', '8261', '8629', '1441', '5139', 's', 'm', '6463', 'u', 'z']
answer:
m, q, s, u, w, x, z


question:
['r', '6797', '657', '7691', '8317', '1897', '859', '5585', 'f', '1957', 'k', '6371', '193', '6177', 'f', '6381', '9095', 'k', 'e', 'q', 'b', '7881', '5117', '8065', 'a', '2495']
answer:

a, b, e, f, k, q, r