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:
['5957', 'd', 'i', 'b', 'e', '5565', 'c', 'i', '2919']
answer:
b, c, d, e, i


question:
['1945', 't', '4477', '4439', '6569', '2021', 'y', 't', '2725', '8947', '6921', '1373', '8107', 'g', 'c', 'w', 'x', 'b', '9117', 'k', '6567', '5073', '2307', 'e', 'b', '7405', 'e', 'x', '1419', 'd', 'o', 'n', 'a', '2647', 'z', '1459', 'n', '6137', 'u', 'b', 'q', '4459']
answer:
a, b, c, d, e, g, k, n, o, q, t, u, w, x, y, z


question:
['2859', 'h', 'z', 'o', 'q', '8917', 'i', '7185', 'w']
answer:

h, i, o, q, w, z