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: ['395', '8309', 'v', 'r', 'x', 'j', 'l', 'b', 'c', 'c', '3123', 't', 'a']

SOLUTION: a, b, c, j, l, r, t, v, x

PROBLEM: ['w', '1349', '3393', '7507', '2469', '8531', 'w', '6845', 'k', 'q', '2401', 'f', 'g', 'l', 'n', 'n', 'e', 'q', 'y', 'v', '3077', '4167', 'b', '5517', 'b']

SOLUTION: b, e, f, g, k, l, n, q, v, w, y

PROBLEM: ['o', 'k', 'x', 'y', 'e', 'j', 'w']

SOLUTION:
e, j, k, o, w, x, y