Detailed Instructions: 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: ['3413', '1197', 'n', 'x', '2711', '6595', 'l', 'k', '9361', '2391', 'y', '3135', 'v', 'b', 'a', '2267', 'o', '5699', '5539', '8533', '9605', '2781']
A:
a, b, k, l, n, o, v, x, y