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.

['7997', 'm']
m

['6027', 'v', 'b', 'l', '7853', 'r', 'y', '2919', '3831']
b, l, r, v, y

['g', 'k', 'q', 'd', 'v', '9607', '9225', 'a', '3135', 'l', 'd']

a, d, g, k, l, q, v