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:
['7591', '1403']
answer:
-1


question:
['r', '9489', 'e', 'n', '6323', 'd', '3163', '265', '8587', '7891']
answer:
d, e, n, r


question:
['s', 'd', '5801', '1941', '767', '1449', '9119', 'y', 'l', 'd', 'z', 'o', 'k', 'h', '2505', 'm', 't', '5305', 'q', '3535', 'o', '3909', 'z', '9517', '7675', 'a', 'o', '1095', 'q', 's']
answer:

a, d, h, k, l, m, o, q, s, t, y, z