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: ['k', 'n']

A: k, n
****
Q: ['3147', '9807', '5313', '6311', '737', '1555', '5803', '3437', '5665', '3973', 'o', 'f', '7871', '1721', '7833', '2933', 'b', 'b', 'n', 'm', 'k']

A: b, f, k, m, n, o
****
Q: ['l', 'k', '5551', 'g', 'y', '6359', 'q', '8955', '4505', '5935', '1487', '5499', '1419', '1209', '8409', '9443', '4961', '47', '7367', 'g', 'f', 'm', '8467', '5157', '8593', 'b', 'l', '4679', 'w', 'e', 'f', 'b', 'p', 'h', '4203', 'i', '8247', 'b', 'a', 'x', '6017', '4383', 'g', '3893', '8671']

A:
a, b, e, f, g, h, i, k, l, m, p, q, w, x, y
****