Definition: 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.
Input: ['8957', '4721', 'e', 'r', 'o', '4543', 'x', 'w']

e, o, r, w, x