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.

['k', 'n']
k, n

['l', 'i']
i, l

['1029', 'j', 'x', '4655', 'k', 'u']

j, k, u, x

