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:
['k', 'r', 'f', '4369', 'z', 'z', 'l', '143', 'r', '707', '9167', 'g', '1749', 'i']
answer:
f, g, i, k, l, r, z


question:
['7187', '7081', 'j', 'i', '3725', '6333', 'h', 'f', '6639', 'r', 'n', '3559', '2785']
answer:
f, h, i, j, n, r


question:
['4995', '9329', '6165', 'f', 'z', 'b', '1299', '4331', '849', '1495', 'o', 'w', 'i', 'o', '7915', 'r', 'z', 'g', 'w', 'r', '3551', 'f', '2609', '4621', 's', 'f', '9175', 'p', 'i']
answer:

b, f, g, i, o, p, r, s, w, z