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: ['u', 'o', 'b', 'b', '5873', 'w', 'v', '4171', '7957', '3501', '2563', 'l', 'q']

SOLUTION: b, l, o, q, u, v, w

PROBLEM: ['7441', '7967', '2011', '1383', 'i', '3623', 'b', 'y', 'e', '1593', 'r', 'a', 'd', 'b', '6159', '3931', '989', '435', 'o', 'y', 'j', 'w', '7669', 'y', '5781', 'u', '531', '7467', '3971', '8139', 'w', 'a', '5113', '9461', '8377', '7431', '6975', '6055', '7307', 'v']

SOLUTION: a, b, d, e, i, j, o, r, u, v, w, y

PROBLEM: ['2721', '3495', 'e']

SOLUTION:
e