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:
['57', 'j', 'n', '877', 'u', 'w', 'j', 'f', '8977', 'h', '469', '9417']
answer:
f, h, j, n, u, w


question:
['1487', '8003', 'd', '7237', 'l', 'y', '2749', 'e', '9685', '2825', 'z', '7743', 'r', '9617', 'w', '4323', '2173', '8419', '2831', '8923', 'l', '2985', '303', 'y', '9409', 'i', 'h', 'e']
answer:
d, e, h, i, l, r, w, y, z


question:
['4891', 'y', '8311', '9179', 'i', 'r', 'l', 'b', 'c', 's', 'p', '579', 'd', '7193', 'l', '2173', '7585', '7135', '4559', '7129', 'q', 'z', '3249', '9019', 'x', '8423', '4845']
answer:

b, c, d, i, l, p, q, r, s, x, y, z