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: ['2995', '25', 'x', 'd', '6247', 'm', 'r', '4319', 's']

d, m, r, s, x