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:
['4857', 'z', '313', '7813', '9935', 'o', 'w', 'i', 'x', 'o', 'e', 's', 'a', 'p', 'i', 'v', 'x', '6743', 'p', '435', 'u', 'a', 'h', '607', '2491', '6159', 'u', '7761', '6197', '3449', '3459', 'e', 'g', '8731', '335', '2883', '3941', 'n', '1881', 'y', 'j', '8189', 'k', '7593', '2747']
answer:
a, e, g, h, i, j, k, n, o, p, s, u, v, w, x, y, z


question:
['2593', '1835', '5089', 'v', '9723', 'f', '9279', '4257', '2175', '655', 'q', 's', 'v', 'j', 'm', '4471', '6419', '1685', '2793', 'x', '509', 's', '4833', '2125', 'b', '6379', '1075']
answer:
b, f, j, m, q, s, v, x


question:
['x', '7901', '5963', 'v', '1645', '5265', 'q', '1713', 'p', '5055', '8585', 'q', 'k', 's']
answer:

k, p, q, s, v, x