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:
['8319', 'f', 'w', 'w', 'v', '6521', '4503', 'b', 's', 'b', '9651', 'k', '4635', '2195', '7537', '6839', 'i', 'd', 'b', '205', 'q', '7333', 'q', '5129', '4921', 's']
answer:
b, d, f, i, k, q, s, v, w


question:
['g', '8591', '4463', '2189', '7901', '1457', 'f', 'i', '9031', 'r', '5519', '3955', 'd', '2093', 'c', 'y', '6591', '6463', 'h', '4371', '111', 'p', '3221', '4185', 'p', '8761', 'w', 'p']
answer:
c, d, f, g, h, i, p, r, w, y


question:
['2203', 'v', '7427', '9711', 's', 'r', 'k', 'o', 'm', '9221', '2633', 'm', 'u', '1113', 'a', 'f', 's', 'u', 'l', '3921', '8799', '5801']
answer:

a, f, k, l, m, o, r, s, u, v