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: ['5463', '5683', 'w', '4071', '3997', 'i', '9677', 'q', 'l', 'v', 'w', '5325', '197', 'g', 'g', '3227', '3477']

SOLUTION: g, i, l, q, v, w

PROBLEM: ['a', '533', '67', 'z', 'z', '9283', 'o', 'a', '7045', '1521', 'm', 'h', 'q', '4173', '7497', '319', '5721', '6097', 'i', '9829', '1801', '7347', 'r', 'z', '239', '4279', 'e', 'k', 'r', 'v', '6653', '599', '8597', 'd', 'r']

SOLUTION: a, d, e, h, i, k, m, o, q, r, v, z

PROBLEM: ['5197', 'o', 'c', 'v', '453', '5433', '7875', 'v', 'q', 'g', 'g', 'b', 'd', 'u', 'x', '129', '1389']

SOLUTION:
b, c, d, g, o, q, u, v, x