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: ['v', '3765', '4065', 'a', '4201', 'f', 'x', '9275', 'q', '9303']

SOLUTION: a, f, q, v, x

PROBLEM: ['m', '5005', 'y', 'h', 'w', '3609', 'p', '2539', '3307', 'p']

SOLUTION: h, m, p, w, y

PROBLEM: ['2313', '5361', 'a', 'g', 'i', '5535', 'a', '6489', '5871', '541', 'v', 'n', 'a', 'l', 'u', 'h', '4125', '6693', 'w', '2755', 'p', 'f', '6627', '4423', 'h', '1503', '6183', '6967']

SOLUTION:
a, f, g, h, i, l, n, p, u, v, w