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: ['r', '2291', 'q', 'e', '8629', '7239', '5277', '7031', 'x']

e, q, r, x