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: ['4641', '2881', 'c', '4827']

SOLUTION: c

PROBLEM: ['1121', 'j', '1433', 'g', 'l', '1479', '1699', 'j', 'a', '8507', 'd', 'a', '5229', 'k', 'x', '4549', 'e', 'p', '1367', 'u', 'd', '785', '215', 'e', 'f', 'a', '101', '7575', '7965', 'p', 'i', '5637', '1005', 'i', 'y', '181', 'r']

SOLUTION: a, d, e, f, g, i, j, k, l, p, r, u, x, y

PROBLEM: ['n', '157', 'r', '6749', 'k', '1829', 'c', 'y', '6079', '1331', 'm', 'y', '5619', 'q', '2623', '9139', '8829', 'p', '925', 'd', 'o', 'f', 'l', 'x', '181', '8421', '1805', '9911', 'x', 'k', '6629', '2699', '4619', '527', '4605', '2083']

SOLUTION:
c, d, f, k, l, m, n, o, p, q, r, x, y