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: ['k', 'v', 'e', '6377', 'y', '3585', '4535', 'f', 'g', 'm', 'f', '8369', 'v', '7445', '4527', '9383', 'n']

SOLUTION: e, f, g, k, m, n, v, y

PROBLEM: ['6585', 'i', 'p', '5623', '3557', '8011', 'c', '6389', 'h', 'h', 'd', '1823', '5567', 'v', 'p', 'x', 'c', '2161', '3649', 'o', '6227', 'f', '9975', 'd', 'm', '2587', 'o', 't', 'k', '7637', 'm', 'l']

SOLUTION: c, d, f, h, i, k, l, m, o, p, t, v, x

PROBLEM: ['a', '5297', '1805', '5117', '1763', '4407', '5761', '6131', 'q', '821', '2029', 'c', 'j', 'm', '8255', 'w', 'e', '4189', 'w', 'c', '7435', 'm', 'z']

SOLUTION:
a, c, e, j, m, q, w, z