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: ['9273', '5219', 'e', '9413', 'v', 'h', '5657', '797', '2303', '2119', '4791', '2757', '4983', 'h', '9681', '4503', '6657', 't', 'i', 'g', '9375', '9901', 'm', 'y', '6461', 'h', '6663', '9493', '5897', '8829', 'd', 'x', '901', '833', 'u']

SOLUTION: d, e, g, h, i, m, t, u, v, x, y

PROBLEM: ['7799', '8163', '3389', 'x', 'k', 'm', '6085', 'f', '1131']

SOLUTION: f, k, m, x

PROBLEM: ['4583', 'z', 'm', 'v', '881', 'e', 'l', 's', 'j', 'd', 'm', '2663', '399', 'n', 'e', '4775', 'e', 'a', '3641', 'k', '2559', '4643', '947', '4905', 'm', '5513', 'r', '7541', '9369', 'b', 'e', 'e', 'p', 'i', 't', '3439', 'c', '2649', 'w', 'z', '4429', 'j', 'f', 'e', '5229']

SOLUTION:
a, b, c, d, e, f, i, j, k, l, m, n, p, r, s, t, v, w, z