TASK DEFINITION: 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.
PROBLEM: ['f', '9027', 'z', '9601', 'w', '7747', '1135', 'j', '1871', 'd', 'u', 'f', 'd', 'x', 'k', '2009', 't', '4625', 'm', '1619', 'm', 'm', '3107', 'x', '3957', '2495', 'j', '201', 'a', '4635', 'r', '7407', 'b', 'r', 'z']

SOLUTION: a, b, d, f, j, k, m, r, t, u, w, x, z

PROBLEM: ['4857', 'z', '313', '7813', '9935', 'o', 'w', 'i', 'x', 'o', 'e', 's', 'a', 'p', 'i', 'v', 'x', '6743', 'p', '435', 'u', 'a', 'h', '607', '2491', '6159', 'u', '7761', '6197', '3449', '3459', 'e', 'g', '8731', '335', '2883', '3941', 'n', '1881', 'y', 'j', '8189', 'k', '7593', '2747']

SOLUTION: a, e, g, h, i, j, k, n, o, p, s, u, v, w, x, y, z

PROBLEM: ['c', 'u', '1713', 'x', '4433', 'y', 'z', '9515', 'r', 'h', 'a', '905', '6179', 'r', 'c', '7593', 't', '8833', 'n', 'j', 'j', '7403', '4145', '2307', '9731', '5329', 'u', '405', 'd', 'k', 'l', 'o', 'i', 'a', 'w', '9173', '3767', '3967', 'm', 'q', 'h']

SOLUTION:
a, c, d, h, i, j, k, l, m, n, o, q, r, t, u, w, x, y, z