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: ['u', 'w', '401', 't', 'g', 'h', 'g', '8073', '9597', '1347', '7835', '5007', '977', 'p', '7679', 'b', '4883', '4931', '999', 'r', '1181', 'x', '2063', 'l', 'w', 'i', 'l', 'x', 'i', '9057', '5007', 'w', '743', '1635', 'y', 'f', '9227', 'z', '5227', 'd', '7129', 'k', '7657']

Answer: b, d, f, g, h, i, k, l, p, r, t, u, w, x, y, z


Question: ['4213', '3595', '7937', 'y', '5723', 'v', 'b', '7007']

Answer: b, v, y


Question: ['8433', '2579', '8981', 'j', '5011', 'b', 'm', '5767', 'b', 'h', '557', 'k', '5615', 'l', 'i', '9877', '7661', '5487', 'n', '8469', '3421', 'i', '9107', 'i', 'x', '5301', 'y', '7773', '8955', 'x', '115', '7273', '6857', '225', 'g', '5941', '1813', 'u', '9031', '2737', 'j', 'k', '9563']

Answer:
b, g, h, i, j, k, l, m, n, u, x, y