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:
['1449', 'a', '6261', '303', '4651', 'n', 'u', '1595']
answer:
a, n, u


question:
['p', '2923', 'e', 'k', '5433', '605', '5079', 'k', 'p', 'x', '4845', '4099', '6795']
answer:
e, k, p, x


question:
['2329', 'i']
answer:

i