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.

['1449', 'a', '6261', '303', '4651', 'n', 'u', '1595']
a, n, u

['w', '743', '5757', '8731', 'k', 'p', '317', 'n', 'x', '5649', 'l', 'm', 'c', '2499', 'l']
c, k, l, m, n, p, w, x

['5399', 'l', '9411', 'f', '1077', 'x', '4539', 'k', 'q', '5695', '4819']

f, k, l, q, x