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: ['j', '4395', '7529', 'h', '929', '4239', '6281', 'u', '1383', 'n', 'u', '591', 't']

h, j, n, t, u