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: ['s', 'c', 'e', '2457', '9413', 'r', '9949', 's', 'z', 'e', 'a', 'o', '7207']

SOLUTION: a, c, e, o, r, s, z

PROBLEM: ['8281', '4831', '1329', 'g', 'e', '8879', 'n', 's', 'x', 'j', '6305', 'j', '921', '3677', '5107', 'n', 'j', '9285', 'a', '5329', '6671', 'c', '9283', 'l', 'a', '7907', 'q', '7605', '855', '6477']

SOLUTION: a, c, e, g, j, l, n, q, s, x

PROBLEM: ['k', '863', 'o', 'j', '8939', 'j', 'x', '6349', '2183', 'i', '9303', '3689', '8821', 'z', '2489', '151', 'c', '8569', 'z', 'e', '6423', '5227', 's', '841', '2775', '7955', '5485', 'f', '1867', 's']

SOLUTION:
c, e, f, i, j, k, o, s, x, z