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:
['8381', 'j', '761', '5431', '7601', 'd', '4339', '1479', 'b', 'x', 'f', 'w', '2437', '7725', '6385', '411', 'w', 'w', 'i', '2769', '5709', '5703', 'k', '5301', '6503', '7833', 'y', '3813', '7061', '5531', 'n', '2251', 'y', '8941', '8481', 's', 't', 't', '3345', 'k', '1545']
answer:
b, d, f, i, j, k, n, s, t, w, x, y


question:
['395', '8309', 'v', 'r', 'x', 'j', 'l', 'b', 'c', 'c', '3123', 't', 'a']
answer:
a, b, c, j, l, r, t, v, x


question:
['o', '9149', '5975', 'z', 'x', 'b', '2709', '2171', '7975', 'i', '663', '5107', 'o', 's', 'x', 'r', '917', 'r']
answer:

b, i, o, r, s, x, z