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:
['7109', '1243', 'f', 'z', 'h', 'd', '6169', 'v', 'h', '3609', '3181', 'd', '3661', '7193', '7341', '9127', 'r', '1623', '5813', 's', 'd', '4011', '4983', 'n', '4195']
answer:
d, f, h, n, r, s, v, z


question:
['6709', 't', 'n', 'k', '991', 'a', '8899', '3563', '527', 'm', '4599', '6679', 'm', 'x', 'f', 'o', '3275', 'x', '677', 'b', '3329', '3593', '5183', '5753', 'u', '6045', '2607', 'y', '9873']
answer:
a, b, f, k, m, n, o, t, u, x, y


question:
['2257', 'm', 'a', '7549', '4749', '8879', 'd', 'q', '1953', 'a', 'k', 'm', '7885', '83', 'u', 'o', '7407', '3415', '1213', '4507', '5031', '3421', '9571', 't', '4009', '8439', '2839', '8045', 'h']
answer:

a, d, h, k, m, o, q, t, u