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:
['6575', '2057', '2135', '6259', '7741', '4919', '7461', 'v', '401', 'h', 'u', '2391', '2181', 'y', '9273', 'd', 'b', 's', '7993', '9323', 'b', '7015']
answer:
b, d, h, s, u, v, y


question:
['4927', 'h', 'x', '4719', 'j', 'f', '7797', 'l', 'i', 'q', 'x', 'i', 'k', '3215', 'k', '1625', 'g', 't', 'i', 'w', 'n', '6659', '8355', '831', 'h', '9723']
answer:
f, g, h, i, j, k, l, n, q, t, w, x


question:
['m', '9897', 'v', 'f', '7509', 't', '1783', '5551', '1855', 'k', '5159', 'u', '7315', '5569', 'g', 'd', 'e', 'y', 'w', 'w', '1353', '7727', '65', '4521', 'w', 'h', '4687', '555', 'h', '9789', '6301', 'q', 'o', '9053', '1899', '7295']
answer:

d, e, f, g, h, k, m, o, q, t, u, v, w, y