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: ['1931', 'c', 's', '8767', 'z', '8977', '9249', '365', 'p', '7187', 'p', '961', 'k', 'k', '423', '5999', '4697', '6251', '6441', '1821', 's', 's', 'f', '5365', 'z', '5113', 'y', 'k', 'i', '5627', 'u', 'w', '4103', '8035', '7105', 'o', 'n', 's', 'y']

SOLUTION: c, f, i, k, n, o, p, s, u, w, y, z

PROBLEM: ['i', 'k', 'j', '4569', '8973', 'm', 'm', '5821', '7675', '669', 'e', '8245', 'y', '6195', 'u', 'q', '3113', 'p', '5231', '3097', '4861', '1311', '9373', 'z', 'x']

SOLUTION:
e, i, j, k, m, p, q, u, x, y, z