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:
['8879', 'x', '1383', '4925', '2867', 'j', 't', 'e', 'w', 'p', 't', 'w', 'l', '7447', '1877', '7747', 'k', 'b', 'x', '8565', 'q', '8575', '5711', '2949', '5637', '2197', '4905']
answer:
b, e, j, k, l, p, q, t, w, x


question:
['8489', 'h']
answer:
h


question:
['2681', 't', 't', '5785', '5965', '4769', 'c', 'z']
answer:

c, t, z