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.

['9579', 'm', 'v', 'r']
m, r, v

['d', '771', '4193', 'e', '1537', 'a', 'q']
a, d, e, q

['2771', '1129', 'a', 'p', 'y', '1847', '87', '439', 'y', '4241', '5759', '3329', 'r', 'n', '9515', 'r', '9441', '9917', 'x', '4673', 'y', 'u', '9093', 'k', 'x', '7951', '779', '8017', 'e', '8559', 'y', 'k', 'b', '7349', 'h', 'e', 'l', '7627']

a, b, e, h, k, l, n, p, r, u, x, y