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: ['p', 'k', 'i', '753', 'u', 'm', '3817', '1597', 'l', 'm', 'a', 'i', 'b', 's', 'c', '2561', 'x', '5363', '1173', '8657', '2033', 'b', 'p', '3093', 'k', '6535', '307', '9925', 'b', 'q', 'q']

SOLUTION: a, b, c, i, k, l, m, p, q, s, u, x

PROBLEM: ['7839', '849', '5651', '4275', 'e', '5453', 'h', '2099', '485', 'i', 'm', 'n', '6563', '5675', '4001', 'h', 'm', 'z', '3467', '4237', '5035', '5609', '8475', '5171', 'v', '3883', '8461', '8611', '4853', 'd']

SOLUTION: d, e, h, i, m, n, v, z

PROBLEM: ['p', 'a', '4473', 't', '5829', '2713', 'i', 'p', '7887', '2137', '6675', 'p', 'm', '6443', '8087', '2657', '8411', '7049', '5395', 'y', '1861', '1787', 'c', 'f', 'p', 'y', '6549', 'o', '7263', '6835', 'e', '8409', 'e', 'g', '7461', 'w', 's', 'e', 'b', '27']

SOLUTION:
a, b, c, e, f, g, i, m, o, p, s, t, w, y