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:
['5181', '8651', '963', '2111', 'g', '7913', '8335', 'o', '1387', '9225', '6517', 's', 'r', '2291', '3699', 'y', 'y', '4223', 'i', '9109', 'm', 's', '8585', 'l']
answer:
g, i, l, m, o, r, s, y


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:
['k', 'f', 'k', 'k', '7883', '307', 'u', '7629', '3177']
answer:

f, k, u