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', 'q', '6461', 's', '8565', '2237', '2071', '8143', '2977', '5511', 'j', 'o', '5793', 'j', 'm', 'n', '8031', 'j', '535', '5001', 's', 'y', '1737']
answer:
j, m, n, o, q, s, y


question:
['8381', 'j', '761', '5431', '7601', 'd', '4339', '1479', 'b', 'x', 'f', 'w', '2437', '7725', '6385', '411', 'w', 'w', 'i', '2769', '5709', '5703', 'k', '5301', '6503', '7833', 'y', '3813', '7061', '5531', 'n', '2251', 'y', '8941', '8481', 's', 't', 't', '3345', 'k', '1545']
answer:
b, d, f, i, j, k, n, s, t, w, x, y


question:
['1927', 'u', '4213', '9371', '1083', 'g', 'y', '7571', 'k', 'g', '1423', '4373', 'k', '6857', '6771', 'f', '4827', '4449', 'x', '8643', 't', 'p', '4969', '9007', 'a', 'j', 'v', '1055', '9689', '4697', 'u', 'e', 'e', '9953', 'h', '8379', '295', 'i', '4653']
answer:

a, e, f, g, h, i, j, k, p, t, u, v, x, y