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:
['h', 'g', '4563', 'v', 'm', '107']
answer:
g, h, m, v


question:
['c', '4881', '6893', '3729', 'j', '2385', 'q', 'v']
answer:
c, j, q, v


question:
['4853', 's', '4409', 'i', 'a', 'v', 't', '1925', '3213', 'x', '8637', 'y', '3057', '201', 'i', '5231', 'x', '6281', '3673', '4081', '7729', 'c', '1213', 't', '355', 'f', 'f', '6159', 'o', 'h', 'j', 'm', '9459']
answer:

a, c, f, h, i, j, m, o, s, t, v, x, y