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:
['2409', 'q', 'w', 'e', 'x', '4737', 'w']
answer:
e, q, w, x


question:
['h', 'l', 'i', '1507', 'h', '409', '6777', 'u', '5563', '6113', '6513', '9949', '461', 'z', 'm', '2519', 'r', '4699', 'n', 'x', '4645']
answer:
h, i, l, m, n, r, u, x, z


question:
['g', 'n', '1071', '1155', '9745', 'v', 'k', 'h', 'e', 'g', '8901', '5107', '317', '9509', '7847', '689', 'm', 't', '6533', '587', 's', 'l', 'v', 'y', 'z', '1623', '3309']
answer:

e, g, h, k, l, m, n, s, t, v, y, z