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: ['d', '2359', '6571', 'c', 'n', 'u', '9513', '9321', '1689', 'b', '969', '1823', 'e', 'b', '9147', 's', '1811', 'k', '5443', '8699', '5483', 'v', 'w', 'n', '1215']

SOLUTION: b, c, d, e, k, n, s, u, v, w

PROBLEM: ['277', '8697', 'q', '2023', '5723', 'm', '8673', 'f', 'z', 'z', 'a', '9875', 'p', 'x', 'l', 'z', 'x', '619', '6509', 's', '2067', '571', 't']

SOLUTION: a, f, l, m, p, q, s, t, x, z

PROBLEM: ['8809', '8641', '5095', '6283', '1953', '1091', 'd', 'g', '2623', 's', 'w', 'm', 'f', '4567', 'a', 'y', 'h', '7173', 'v', 'e', '8505', 'u', 'i', 'w', 'u', '9813', 'j', '6077', '6025', 'o', 's', 'b', '8353', 'u', 'k', 'y', 'w', 'e', 'y', 'b', 'g', 'l', 'i', '415']

SOLUTION:
a, b, d, e, f, g, h, i, j, k, l, m, o, s, u, v, w, y