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.

['9025', '3259', '4863', 'u', '6443', '9931', '627', 'x']
u, x

['b', 'd', '8153', 'u', '3695', '5317']
b, d, u

['z', 'd', '4247', 's', 'k', '6361']

d, k, s, z