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: ['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: ['8381', 'j', '761', '5431', '7601', 'd', '4339', '1479', 'b', 'x', 'f', 'w', '2437', '7725', '6385', '411', 'w', 'w', 'i', '2769', '5709', '5703', 'k', '5301', '6503', '7833', 'y', '3813', '7061', '5531', 'n', '2251', 'y', '8941', '8481', 's', 't', 't', '3345', 'k', '1545']

SOLUTION: b, d, f, i, j, k, n, s, t, w, x, y

PROBLEM: ['9697', '6183', 'y', 'x', 'l', 'h', '7873', '2569', '9697', '285', 'h', '2225', '4257', '6905', 'n', 't', '4201', '7441', 'h', '695', '2297', 'o', 'w', '357', '3055', '4743', '8093', '3315', 's', 'h', '6449', '5621', '4673', '4427']

SOLUTION:
h, l, n, o, s, t, w, x, y