instruction:
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.
question:
['w', '8777', 'y', 'e', '8015', 't', 'w', '53', '9149', 'e', 'k', '1837', 'b', 's', '4007', '4905']
answer:
b, e, k, s, t, w, y


question:
['7799', '8163', '3389', 'x', 'k', 'm', '6085', 'f', '1131']
answer:
f, k, m, x


question:
['l', 'y', 'x', '2111', '4233', '5963', 'h', 'g', 's', 'x', '8881', 'f', '5517', 'h', 'o', 'e', '4809', '2225', 'k', '547', '4127', '4519', 'r', '8891', 'f', '1581', '5443', '8757', 'p', '6669', '5695', '1451', 'n', '4699', '3167', '551']
answer:

e, f, g, h, k, l, n, o, p, r, s, x, y