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.

Q: ['k', 'c', 'i']

A: c, i, k
****
Q: ['d', '4377', '9271', '8053', '9519']

A: d
****
Q: ['c', 'a', 'k']

A:
a, c, k
****