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: ['9403', '9881', '8391', 't', '1793', 'w', 'x', 'y', '6383', 'j', 'r', '5323', 'r', 'l', 'e', 'u', '7193', '2309', '837', 'z', 'w', 'n', '4427', '8269', '6333', 'a', 'p', '1933', '8497', '2665', '1349', '6807', '9009', 'b']

SOLUTION: a, b, e, j, l, n, p, r, t, u, w, x, y, z

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: ['1087', 'l', '6343', '3653', 'u', '8009', '5441', 'e', '8021', '2499', '2857', '7969', 'e', '8729', '5393', 'e', 'x', 'f', 'f', 'b', '5667', 'j', 'y', 'o', 'b', 'y', 'o', '667', '9315', '2253', 'm']

SOLUTION:
b, e, f, j, l, m, o, u, x, y