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:
['a', 'a', 'b']
answer:
a, b


question:
['4945', 'i', 'h', 's', '8925', 'i', '3995', 'f', '813', '1823', '3475', 'q', '2463', '9487', 'c', 'c', 'n', 'y', 's', '6269', 'a', 'u', 'd', 'd', '9291', '3187', '545', '7929', 'd', '1007', '7579', '8421', '4033', 'v', 'c', 'e', 'n', 'j']
answer:
a, c, d, e, f, h, i, j, n, q, s, u, v, y


question:
['u', '2729', 'p', 'n', 'y', '5021', 'b', '3511', '3949', '193', '2015', 'p']
answer:

b, n, p, u, y