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: ['5463', '5683', 'w', '4071', '3997', 'i', '9677', 'q', 'l', 'v', 'w', '5325', '197', 'g', 'g', '3227', '3477']

SOLUTION: g, i, l, q, v, w

PROBLEM: ['5011', 'l', '925', 'e', 'b', '3077', 'm', '4541', '781']

SOLUTION: b, e, l, m

PROBLEM: ['b', 'v', '2169', 'g', '4439', '1333', '6537', 'h', 'd', 'n', 'm', 'p', '4167', 'f', '2675', '307', 'm', 'm', '535', '7185', 'v', '9105', 'm', 'w', '5107', 'a', 'x', 'b', 'u', '7535', 'm', '8945']

SOLUTION:
a, b, d, f, g, h, m, n, p, u, v, w, x