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.

Q: ['6769', '1057', '1021', 'n', '8231', '9173', '8123', 'a', '6053', 'q', 'y', '883', 'r', '1215', 'x', 'o', '9531']

A: a, n, o, q, r, x, y
****
Q: ['n', 't', '2901', '9697', 'a', 'j', 'x', 'a', '4437', '2255', '2177', 's', '3173', 'j', 't', '5713', '4091', '4253', '5553', 'i', '4533', 'i', 'e', '6899', 's', '3541', '2139', '2705', 'm', 'u']

A: a, e, i, j, m, n, s, t, u, x
****
Q: ['k', '4481', '4303', 'j', 'l', '5173', '1993', 'a', '3197', 'y', '9167', '1323', 'z', 'p', 'i', '9635', '195', 'a', 'i', '3881', '4391']

A:
a, i, j, k, l, p, y, z
****