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: ['1945', 't', '4477', '4439', '6569', '2021', 'y', 't', '2725', '8947', '6921', '1373', '8107', 'g', 'c', 'w', 'x', 'b', '9117', 'k', '6567', '5073', '2307', 'e', 'b', '7405', 'e', 'x', '1419', 'd', 'o', 'n', 'a', '2647', 'z', '1459', 'n', '6137', 'u', 'b', 'q', '4459']

Answer: a, b, c, d, e, g, k, n, o, q, t, u, w, x, y, z


Question: ['r', 'y', 'c', '3211', '9245', '8459', '8521', '5781', 'w', 's', 'd', '5299', 'a', 'y', 'g', 'm', '6435', '8605', 'e', 'h', '6871', 's', '387', 'l', '5829', 'e', 'd', '9545', '2945', 'k', 'v', 't', '8449', '2199', 'm', '2599', '1489', '6623', 'x', 'l']

Answer: a, c, d, e, g, h, k, l, m, r, s, t, v, w, x, y


Question: ['7693', 'x', 'r', 'm', 'c', 'j', 'z', 'p', 'a', 'i', 'o', 't', '7169', 'n', '335', '5731', '5463', 'a', 'r', 'w', 'p', 'd', 't', 'g', '2319', 'p', '937', 'm', '3161', '6315', '519', '9395']

Answer:
a, c, d, g, i, j, m, n, o, p, r, t, w, x, z