Detailed Instructions: 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.
Q: ['e', '2355', '7771', '6671', '6145', '4391', '4763', 'n', 'q', 'b', '1135', 'w', '929']
A:
b, e, n, q, w