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:
['9483', '501', 'j', 'k', '3103']
answer:
j, k


question:
['s', 'u']
answer:
s, u


question:
['d', 'o', 'n', '4029', '2543', '1621', 'p', '2825', 'x', '9321', '295', 'd', 'b', '8179', '5591', 'e', '5959', '2647', '661']
answer:

b, d, e, n, o, p, x