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: ['6175', '9441', '7127', '5979', 's', '1367', 'e', 'm', '7083', '1787', '8375', '2851', '3475', 'r', '697', 'g', 'z', 'm', '4207', 'c', '7971', 'z', '9339', 'd', 's', '3507', '9003', 'i', 'y', 'w', 'j', 'i']

SOLUTION: c, d, e, g, i, j, m, r, s, w, y, z

PROBLEM: ['d', 'm', 'k', '3513', '8241', '5541', 'm', 's', '1993', '6163', '2753', 'd', 'b', 'm', 'i', '7647', '8631', '9119', '2165', 'x', '3911', '2769', '1673', '7195', 't', 'w', '5555', 'o', '3265']

SOLUTION: b, d, i, k, m, o, s, t, w, x

PROBLEM: ['g', '9103', 'r', 'y', '5361', 'l', 'r', '9723', 'g', 's', '6279', '8405', 'd', 'j', '4927', 'h', '3545', '7733', 'c', 'g', '7825', 't', 'q', '1113', 'h', 'g', 'm', '6685', 'e', 'l', '9253', '1943', 'd', 'u']

SOLUTION:
c, d, e, g, h, j, l, m, q, r, s, t, u, y