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:
['7595', '5303', '3985', 'n', 'w', 's', 'r', 'f', '8237', 'q', 'y', 'f', '3121', '2463', '4597', 'q', '6801', 'f', 'i', '8563', '3267', 'k', '6157', 'f']
answer:
f, i, k, n, q, r, s, w, y


question:
['k', '6595', '1595', 'v', 'h', 'b', '8815', '6681', 'j', '7581', 'p', '9095', '5453', 'r', 'y', '7755', 'x', '1853', 'k', 'q', 'u', 'j', 'q', '9651', 'o']
answer:
b, h, j, k, o, p, q, r, u, v, x, y


question:
['v', '749', '9449', '8065', 'z', 'u', '921', 's', 'o', '3589', 'l', '9239']
answer:

l, o, s, u, v, z