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:
['f', '9203', 'w', 'f', '3751', '8095', '1319', 'f', '3017', 'r', 'y', '8221', '2715', '9959']
answer:
f, r, w, y


question:
['o', 'm', '8015', '787', '4787', '1727', 'f', 'e', 'c']
answer:
c, e, f, m, o


question:
['7161', 'c', 'z']
answer:

c, z