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: ['t', 'u', 'y', 'y', 'b', 'x', 'q', '3713', '2679']

SOLUTION: b, q, t, u, x, y

PROBLEM: ['p', '9641', '8515', '1207', 'd', 'j', '6617', '5529', 'g', 'a', 'o', 'f', 'y', '4993', '4643', '6087', 'n', '3177', 'y', '9471', '1229', '8211', '7079']

SOLUTION: a, d, f, g, j, n, o, p, y

PROBLEM: ['3301', 'f', '2685', 'j', '4973', '7381', '4453', '611', '1889', 'e', '3867', 'm', '8473', 'e', '5325', '5193', '9515', 'o', 'k', '989', 'r', '9439', '5121', 'p', 'h', '3087', '9697', '2281', 'q', '6879', '3159', 'b', '4893', 'x', 't']

SOLUTION:
b, e, f, h, j, k, m, o, p, q, r, t, x