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', '8751', '3385', '7299', '5657', 'w', '1013', 'n', 'k', 'k']

k, n, r, w