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:
['j', '917', 'w', 't', '8873', '1431', '8059', '7041']
answer:
j, t, w


question:
['q', 'c', 'o', 'e', 'n', 'q', 'w', '9475', 'w', '863', 'r', '2219', '3483', '5035', '8209', '7957', 'b', '3735', '1423', 'l', '3409', '7639', 'd']
answer:
b, c, d, e, l, n, o, q, r, w


question:
['9769', 'x', '4611', '2825', 'e', 'z', '4067', '7545', 'z', 't', 't', 'p', 'b', 'i', 'v', '2343', 't', 'k', '37', '215', '4393', 'k', 'h', '7691', '9359', 'j']
answer:

b, e, h, i, j, k, p, t, v, x, z