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]: ['6769', '1057', '1021', 'n', '8231', '9173', '8123', 'a', '6053', 'q', 'y', '883', 'r', '1215', 'x', 'o', '9531']
[A]: a, n, o, q, r, x, y


[Q]: ['5971', 'x', 'c']
[A]: c, x


[Q]: ['e', 'y', '531', 'l', 'i', 'f', 'l', '883', '1897', 'i', '1523', 'i', '9267', 'r', 'c', '4321', 'w', '8565', 'c', 'r', 'w', '6893', '4967']
[A]:
c, e, f, i, l, r, w, y