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: ['q', 'z', 'o', '2057', '4319', '6127', '5235', '8919', 'b', '9385', '4893', '1359', '7129', 'o', '1547', 'q', 'n', '4683', 'a', '3865']
A:
a, b, n, o, q, z