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: ['n', 'g', 'u', '2873', 'k', '4411', 'w', '8179', 'w', 'w', 'f', 'g', 'e', '7837', '3055', 'z', 's', '6037', 'n', '1479', 'c', '5311', 'i', 'w', 'z', '1891', '9663', 'y', 'f', 'h']

SOLUTION: c, e, f, g, h, i, k, n, s, u, w, y, z

PROBLEM: ['j', '1733', 'p', '6741', '7933', '8943', '733', 'x', '1107', 'z', '1719', '7653', 'y', 'z', '6563', 'p', '4615', 'j', '4489', 'h', 'w', 'y', 'p', 'c', '7949', 'k', 'm', 'r', '9427', '7243', '9777', 'j', '323', '4095', 't']

SOLUTION: c, h, j, k, m, p, r, t, w, x, y, z

PROBLEM: ['g', '4325', '4673', '9703', '9607', 'h', 'r', 'm', '4289', 'z', 'j', 'a', 'k', 'k', '5385', 'q', '8785', '9501', 'b', '4703', 'v', '8129']

SOLUTION:
a, b, g, h, j, k, m, q, r, v, z