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: ['x', 'o', '8161', 's', '3653', 'v', 'c', 'e', '5353', 'h', '9145', '333', 's', '7689', '8277', 'a', 'o', 'h', 'z', 'w', '9297', 'w', '9383', '8963', 'k', 'x', 's', 'w', 'h', 'j', '5737', 'o', '2247', '3723', '2043', '4615']

SOLUTION: a, c, e, h, j, k, o, s, v, w, x, z

PROBLEM: ['9403', '9881', '8391', 't', '1793', 'w', 'x', 'y', '6383', 'j', 'r', '5323', 'r', 'l', 'e', 'u', '7193', '2309', '837', 'z', 'w', 'n', '4427', '8269', '6333', 'a', 'p', '1933', '8497', '2665', '1349', '6807', '9009', 'b']

SOLUTION: a, b, e, j, l, n, p, r, t, u, w, x, y, z

PROBLEM: ['3921', '857', 'e', 'e', 't', '5319', 'g', 'o', '8361', 'x', '6803', '7469', 'g', 'y', '1435', '2479', 'n', 'a', '6431', 'u']

SOLUTION:
a, e, g, n, o, t, u, x, y