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:
['4925', 'i', 'q', 'k', '7615', 'r', '7217', 'o', '8097', '9151']
answer:
i, k, o, q, r


question:
['t', 'u', 'y', 'y', 'b', 'x', 'q', '3713', '2679']
answer:
b, q, t, u, x, y


question:
['t', '3267', '7797', '8053', 'h', 't', 'c', '5791', '5389', 'e', '2337', '3065', 'r', 'v', '8261', 'l', '8317', '655', '2485']
answer:

c, e, h, l, r, t, v