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.

['4927', 'h', 'x', '4719', 'j', 'f', '7797', 'l', 'i', 'q', 'x', 'i', 'k', '3215', 'k', '1625', 'g', 't', 'i', 'w', 'n', '6659', '8355', '831', 'h', '9723']
f, g, h, i, j, k, l, n, q, t, w, x

['4641', '2881', 'c', '4827']
c

['c', '6397', 'd', '107', 'l', 'x', 'w', '3953', 'v', 'w', '9429']

c, d, l, v, w, x