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: ['m', '7807', 'n', 'w', '5097', '1023', '2723', 'u', '3055', '7285', 'f', 'm', 'w', '5197', '9743', '7519', '4451', 'c', 't', '1939', '5847']

SOLUTION: c, f, m, n, t, u, w

PROBLEM: ['2505', '4199', 'e', '5433', '8795', 'q', 'i', '9357', 'o', '257', '8235', 'b', '1339', 'w', '1463', 'm', '277', '3211', '3863', 'r', 'm', 'i', '5793', '7451', '4787', '4739', 'k', 't', 'o', '7453', '9385', 'v', 'l', 'y', 'f', 'r', 'p', 'w']

SOLUTION: b, e, f, i, k, l, m, o, p, q, r, t, v, w, y

PROBLEM: ['8841', '5731', '5929', 'j', '3163', '6567', '7711', 'm', '2511', 'b', 'v', '7531', '589', '177', '1977', '6883', 'k', 'k', '7067', 'b', 'x', 'f', 'b', '5155', 'h', '7443', '1923', 'd', 'v', 'b', 'p', '5321', 'b', '8823', '1093', '3829']

SOLUTION:
b, d, f, h, j, k, m, p, v, x