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: ['y', 'p', 'q', '2157', 'b', 'w', '8875', 'k', 'i', 'd', '9743', '4941', 'b', 'p', '9941', '495', 'h', 'i', '839', 'c', 'h', 'f', 'b', 'a', 'k', 'z', '7549', '4149', 'h', 'j', '1947', 't', 'f', 'c', '1243']

SOLUTION: a, b, c, d, f, h, i, j, k, p, q, t, w, y, z

PROBLEM: ['t', 'x', '1699', '8727']

SOLUTION: t, x

PROBLEM: ['979', '1653', 'u', 'o', 'e', 'x', 'b', '621', '7141', 'u', 'i', '9961', 'g', 'l', 'o', 'b', 'v', 'g', '7493', 'u', '693', '2757', 'z', 'h', '9443', '9269', 'b', '1939']

SOLUTION:
b, e, g, h, i, l, o, u, v, x, z