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.

[Q]: ['a', 'a', 'b']
[A]: a, b


[Q]: ['u', 'k', 'd', '4393', 'u', 'h', 'q', '833', 'k', 'l', '5749', 'r', '7123', '1003', 'z', '531', 'o', 'u', '6601', '6975', '4905', 'n', 'e']
[A]: d, e, h, k, l, n, o, q, r, u, z


[Q]: ['i', '8157', '6807', '3501', '9315', 's', '2987']
[A]:
i, s