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.

Q: ['w', '6291', '3939', '9569', 'u', '1635', '3359', '8335', 'n', '2799', '7359', 'k', 'm', '2817']

A: k, m, n, u, w
****
Q: ['6143', 'y', '5505', '9813', 'r', 'v', 'u', '8681', '2387', 'u', 'o', 'm', '9793', 'm']

A: m, o, r, u, v, y
****
Q: ['1791', '5225', '7225', '8265', 'i', 'b', 'w', '7823', '4277', '5803', '7701', '3445', '1329', '4121', 'f', '3453', '3239', '2461', 'x', 'o', 'u']

A:
b, f, i, o, u, w, x
****