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: ['7997', 'm']

A: m
****
Q: ['5159', '6407', '4021', '6655', 'c', 'k', 'w', '7191', 'l', '4321', '1609', 'm', '1991', '9261', '511', 'p', '7495', 'b', 'e', '4647', '2711', 'd', 'y', '3835', '5037', '3613', '2695', '3367', 'm', 'j', 'y', '9561', '4889', 'a', 'z', '2253', 'p', 't', 's', '8371', '2859', 's']

A: a, b, c, d, e, j, k, l, m, p, s, t, w, y, z
****
Q: ['589', '1973', '251', 'f', '4729', '5127', '2313', 'r', '9691', 'b', 'q', '9887', '9585', '8567', 'c', '4013', 'n', 'c', 'r', '655']

A:
b, c, f, n, q, r
****