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: ['333', 'b', '261', 'k', 'p', '7861']

Answer: b, k, p


Question: ['y', 'p', 'q', '2157', 'b', 'w', '8875', 'k', 'i', 'd', '9743', '4941', 'b', 'p', '9941', '495', 'h', 'i', '839', 'c', 'h', 'f', 'b', 'a', 'k', 'z', '7549', '4149', 'h', 'j', '1947', 't', 'f', 'c', '1243']

Answer: a, b, c, d, f, h, i, j, k, p, q, t, w, y, z


Question: ['n', '9179', '8351', 'r', 'y', 'e', '9719', '3015', 'c', 'y', '7565', 'o', '2793', 'j', 'q', 'o', '6263', '8887', 'a', '6135', '9231', 'o', 'r', 'g', '6871', 'l', '1557', '6435', '4303', '4841', 'w', '369', 't', 'h', '3469', '65', 'h', 'd', 't', '5521']

Answer:
a, c, d, e, g, h, j, l, n, o, q, r, t, w, y