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:
['2165', 'f', '5081', 's']
answer:
f, s


question:
['d', 'm', 'k', '3513', '8241', '5541', 'm', 's', '1993', '6163', '2753', 'd', 'b', 'm', 'i', '7647', '8631', '9119', '2165', 'x', '3911', '2769', '1673', '7195', 't', 'w', '5555', 'o', '3265']
answer:
b, d, i, k, m, o, s, t, w, x


question:
['8273', 'l', '6843', '6891', 'm', 'b', 'r', '2387', 'm', '6903', 'i', '8917', '4585', 'a', '661', 'c', '369', '9635', 'c', '2843', '1051', 't', '6211', 'x', 'a', 'n', '9655', 'a', 'c', '3657', '8073', '5871', '6445', '5191', 'x', '1047', 'x', '2511', 'l', 'o', 'q', 'd', 'e']
answer:

a, b, c, d, e, i, l, m, n, o, q, r, t, x