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: ['a', 'y', 'v', 'f', 'x', 'k', 'f', 'j', '6245', '6289', 'd', '6909', '8701', 'm', '3277', 'f', 'j', 'j', '9227', '8663', '5771', 'j', 'n', 'u', '7837', 's', '2539', '6363', 'g', 'a', '1009', 'v', '1483', 'x', 'i']

SOLUTION: a, d, f, g, i, j, k, m, n, s, u, v, x, y

PROBLEM: ['459', '1729', 'b', 'c', '9619', '4461', '4347', '6733', 'i', '3631', 's', 'j', 'i', 'r', '5293', 'q', '7397', '4309', 'c', 'n', 'k', '197', 'q', '8139']

SOLUTION: b, c, i, j, k, n, q, r, s

PROBLEM: ['673', 'p', 'j', '5413', 'q', '2343', 'm', 'j', 'p', 'h', '1191', '1377', 'x', '8619', 't', '7655', 'g', '3505', 'e', '5379', '6003', 'm', '6951', '6857', 'h', 'p', '2399', '9095', 'l', 'h', 'b', '685', 'm', 'v', '7581', 'f', 'v', 'k', 'd', '1945']

SOLUTION:
b, d, e, f, g, h, j, k, l, m, p, q, t, v, x