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:
['8005', 'q', 'w', 'a', 'f', 'o', '6017', '7591', 'm', 'p', 'z', 'q', 'u', 'o', 'd', '6043', 'f', '3575', 'r', '2885', 'o', '3141', '621', '2375', 't', '5397', 'h', 'b', 'i', '3785', '1551', 'i', '8879', 'g', '5237', '7111', '2057', '1743', '9895', '2613', 'i', 'z', '677']
answer:
a, b, d, f, g, h, i, m, o, p, q, r, t, u, w, z


question:
['5345', 'f', '6605', 's', 'q', 'w', 'p', 'o', 's', 'u', 'i', '7339', '8379', 'h', '9547', 'b']
answer:
b, f, h, i, o, p, q, s, u, w


question:
['6391', '9531', 'z']
answer:

z