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:
['9579', 'm', 'v', 'r']
answer:
m, r, v


question:
['7677', '4069', 'b', 'w', '4381', 'b', '5757', '711', '765', '8347', '6547', '9527', '945', '5333']
answer:
b, w


question:
['j', 'e', '9485', '1233', 'b', 't', 'u', '5329', 'd', 'c', 'f', 'x', '5735', '5137', 'v', '5645', '935', 'w', 'i', '3215', 'q', 'u', 'v', '9513', '5783', 'v', '4545']
answer:

b, c, d, e, f, i, j, q, t, u, v, w, x