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: ['8829', 'm', '5369', 'q', '5737', '7799', '5705', 'p', 'w', '1983', '4849', 'h', '6771', 'p', 'y', '1071', 'u', '6401', '7723', 'p']

SOLUTION: h, m, p, q, u, w, y

PROBLEM: ['7917', '2295', 'q', 'v', '9373', 'w', 'n', 'q', '5803', 'g', 'k', 'm', '2167', 'k', '6425', 'x', 'g', '341', 't', 'u', '8829', 'h', '4333']

SOLUTION: g, h, k, m, n, q, t, u, v, w, x

PROBLEM: ['o', '7951', '7891', '6121', '7849', '5321', 'o', 'j', 'g', 'l', '9009', 'h', 'r', '2313', '6371', 'm', 'o', '8789', '4891', '7357', 'n', '5507', '5581', 'd', '3335', 'v']

SOLUTION:
d, g, h, j, l, m, n, o, r, v