instruction:
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.
question:
['d', '6003', 'k', '1987', '1877', 'a', '2615', 'n', 's', 'f', 'b', 'm', '1149', '8293', '5803', 'e', '2697', '5917', 'p', '6035', '2385', 'i', 'u', 'm', '9565', '4523', 'b', 'v', '2577', '9725', '6093', '6203', '4197', '8477', 'o', 'd', '3637', '9827', '5523', '7189', 'j', '8893', 'h', 'q']
answer:
a, b, d, e, f, h, i, j, k, m, n, o, p, q, s, u, v


question:
['w', '8777', 'y', 'e', '8015', 't', 'w', '53', '9149', 'e', 'k', '1837', 'b', 's', '4007', '4905']
answer:
b, e, k, s, t, w, y


question:
['3957', 'q']
answer:

q