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: ['2593', '1835', '5089', 'v', '9723', 'f', '9279', '4257', '2175', '655', 'q', 's', 'v', 'j', 'm', '4471', '6419', '1685', '2793', 'x', '509', 's', '4833', '2125', 'b', '6379', '1075']

SOLUTION: b, f, j, m, q, s, v, x

PROBLEM: ['c', 'a', 'p', 'p', '4203', '1587', '2953', '9809', '99', '5821', 't', 'i', '4213', '1809', 's', 'l', 'i', 'b', '9233', '3983', '7713', '1807', 'k', 'f', '7825', '5491', 'o', '1347', 'u', 'h', '3967', 'u', 'g', '6775', '1069', '9211', 'i', '3369', 'r']

SOLUTION: a, b, c, f, g, h, i, k, l, o, p, r, s, t, u

PROBLEM: ['4143', '1929', '1875', '1447', 'b', 'g', '9211', '8329', 'h', 'f', '63', 'j', '6107', '6543', 'k', '8975', '9203', '4819', '7137', '5761', '7191']

SOLUTION:
b, f, g, h, j, k