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: ['n', 'y', '7087', '9539', 'x', 'i', 'w', '7237', '8613', 'k', '5999', '4179', 'o', 'm', '7485', '1955', 'w', '1451', 'h']

SOLUTION: h, i, k, m, n, o, w, x, y

PROBLEM: ['j', 'y', '9907', 'a', '5715', 'l', '9817', '1949', '2697', '2255', '9571', '8957', '9329', '6055', 'z', 'q', '1185', '4593']

SOLUTION: a, j, l, q, y, z

PROBLEM: ['e', 'z', '743', '6471', '2393', '2595', '7511', 'p', 'o', 'x', '4279', '1465', '4977', 'u', '3309', '9377', 'n', 'w', '3177', 'l', '3225', '3663', '4973', 'm', 'x', 'f', 'w', '7441', '6943', 'c', '301', 'u', 'r', 'k', 'a', '5371', '5237', 'q']

SOLUTION:
a, c, e, f, k, l, m, n, o, p, q, r, u, w, x, z