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: ['w', 'o', 'l', '1857', 's', 'q', 'j', 'e', '5945', 'g', 'l', '9563', 'e', 'u', '7633', '7977', '4943', 'y', '5621', 'f', '1653', 'c', 'l', '2843', '2125', '7731', '5257', '5667', 'b', 'b', '5765', 'a', 't', '8163', '9785', '5385']

SOLUTION: a, b, c, e, f, g, j, l, o, q, s, t, u, w, y

PROBLEM: ['o', 'm', '8015', '787', '4787', '1727', 'f', 'e', 'c']

SOLUTION: c, e, f, m, o

PROBLEM: ['o', '5865', 'c', 'u', '6053', 'b', 'b']

SOLUTION:
b, c, o, u