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: ['5159', '6407', '4021', '6655', 'c', 'k', 'w', '7191', 'l', '4321', '1609', 'm', '1991', '9261', '511', 'p', '7495', 'b', 'e', '4647', '2711', 'd', 'y', '3835', '5037', '3613', '2695', '3367', 'm', 'j', 'y', '9561', '4889', 'a', 'z', '2253', 'p', 't', 's', '8371', '2859', 's']

SOLUTION: a, b, c, d, e, j, k, l, m, p, s, t, w, y, z

PROBLEM: ['3627', '2051', '3203', 'c', 'r', 'a', '1453', 'e', 'z', 't', '1093', '4651', 'a', 'f', '8159', '9623', 'l', 't', 'r', '6963', '7071', '8103', '3493', 'y', '2369', '609', '2011', 'f', '187', 'f', 'c']

SOLUTION: a, c, e, f, l, r, t, y, z

PROBLEM: ['1499', '9631', 'z', 'k', '1367', '7955', 'p', '9441', '725', 'i', '1113', '1515', 'v', 'g', '6359', 'a', 'v', '6473', 'o', 'o', 'b', '781', 'j', 'a', '2069', '3343', '7153', '9281', '4523', 'w', 'z', '7449', 'g', '807', '6591', '4023', 'k', 'q', '449', '2215', '6227', 'l', '7459']

SOLUTION:
a, b, g, i, j, k, l, o, p, q, v, w, z