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: ['653', '1969', '6235', '6283', 'd', 'e', '465', 'e']

SOLUTION: d, e

PROBLEM: ['4927', 'h', 'x', '4719', 'j', 'f', '7797', 'l', 'i', 'q', 'x', 'i', 'k', '3215', 'k', '1625', 'g', 't', 'i', 'w', 'n', '6659', '8355', '831', 'h', '9723']

SOLUTION: f, g, h, i, j, k, l, n, q, t, w, x

PROBLEM: ['i', 'b', 'v', 'e', 'o', 't', 'b', '2689', '8395', '8631', 'b', 'p', 'n', 'l', '1801']

SOLUTION:
b, e, i, l, n, o, p, t, v