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: ['u', 'i', '1185', '3795', '5417', 'k', 'b', '2629', '2635', 'z']

SOLUTION: b, i, k, u, z

PROBLEM: ['3947', '4809', 'b', 'a', '4769', '4179', '535', '5965', 'f', 'j', '2265', 'w', '3103', 'u']

SOLUTION: a, b, f, j, u, w

PROBLEM: ['n', 'n', '1213', '9121', '9699', 'j', 'k', 'n', 'w', 's', '5697', '8657', 'x', '7245', 'b', 'd', '9929', 'd', '4213', 'v', 'v', '9643', '7749', 'k', 'y', 'h', 'z', '4373', '4793', 'z', 'l', '2795', 'n', 'q', '5703', '5165', 'm', 'v', '4937', '4279', 'i', 'y', '825', '3475']

SOLUTION:
b, d, h, i, j, k, l, m, n, q, s, v, w, x, y, z