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:
['8495', 'p', 'j', 'm', 'n', '9115', '1183', 'r', 'r', '8735', 'a', 'i', 'k', 'p', '8927', 'r', '9283', '9563', 'g', '2503', 'h', '1091', '5257', 'a', '3061', '2835', 'l', 'w', 'j', '7617', '8793', '7463', 'h', '8467', '7337', 'b', '4655', 'd']
answer:
a, b, d, g, h, i, j, k, l, m, n, p, r, w


question:
['9947', '3353', '8643', '4621', '4857', 'y', '7075', 'c', '8911']
answer:
c, y


question:
['8797', 'o', 'm', 'x', 'o', 'y', 'y', '7091', '5811']
answer:

m, o, x, y