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.

[EX Q]: ['9923', 'x', '1901', 'v', '1459', '7503', '3829', '4929', 'k', 'c', '3329', '8793', 'n', 'a', '7249', 'b', 'l', 'l', 'm', 'p', 'b', 'a']
[EX A]: a, b, c, k, l, m, n, p, v, x

[EX Q]: ['749', 'r', 'a', 's', 't', '5905', 'm', 'd', '8437', '4583']
[EX A]: a, d, m, r, s, t

[EX Q]: ['s', '4501', '5483', '7069', '4537', '6785', '2681', 'c', '6131', '713', '8585', 'w', '193', 'u', 'b', '7841']
[EX A]:
b, c, s, u, w