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: ['p', '5229', '7521', 'y', 'n', 'u', 'c', '4047', '781', 'a', '4707', '7149', 'j', 'm', 't', '515', '7691', 'h', '4879', 'j', '6593', 'n', 'p', '2949', '1343', 'y', '2629', 'p', 'b', 'b', '2861', 'a']

SOLUTION: a, b, c, h, j, m, n, p, t, u, y

PROBLEM: ['5163', 'n', 'j', '67', '3801', 'n', '7113', 'z', '579', '6885', '8921', 'v', '5481', '5507', 'k', '8403', 'c', '837', 'u', '6341', 'd', 'i', '497']

SOLUTION: c, d, i, j, k, n, u, v, z

PROBLEM: ['5705', 'k', '879', '6985', '1235', '6021', '873', 'w', 'a', 'n', '1603', '6119', '3857', '6611', 'q', 'f', '9685', '2249', '2925', '3789', 'z', '691', 'y', 'e', 'q', 'v', 'z', '887', '7601', '9527', 's', 'm', '8863', 'h', '4489', 'u', '9919', 'j', 'b']

SOLUTION:
a, b, e, f, h, j, k, m, n, q, s, u, v, w, y, z