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:
['5011', 'l', '925', 'e', 'b', '3077', 'm', '4541', '781']
answer:
b, e, l, m


question:
['6027', 'v', 'b', 'l', '7853', 'r', 'y', '2919', '3831']
answer:
b, l, r, v, y


question:
['131', 'h', '7199', 'h', 'v']
answer:

h, v