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.

['5011', 'l', '925', 'e', 'b', '3077', 'm', '4541', '781']
b, e, l, m

['7595', '5303', '3985', 'n', 'w', 's', 'r', 'f', '8237', 'q', 'y', 'f', '3121', '2463', '4597', 'q', '6801', 'f', 'i', '8563', '3267', 'k', '6157', 'f']
f, i, k, n, q, r, s, w, y

['5481', '983', 'v', 's', 'l', 'e', '6805', '8629', 'a', 'b', '5977', 'd', '1779', '8153', '935', '6045', 'p', '9655', '2147', 'p', '6317', 'w', '1641', '1555', '2647', '677', '7883', '4095']

a, b, d, e, l, p, s, v, w