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:
['7677', '4069', 'b', 'w', '4381', 'b', '5757', '711', '765', '8347', '6547', '9527', '945', '5333']
answer:
b, w


question:
['1627', 'r', '2429', 'b', '4451', 's', 'k', 'm', '269', 'l', '709', 's', 'q', '985', 'x', 'j', 'k', 'k', '6603', 'v', '9497', '477', '5803', 'c', 't', 'f', '3189', '6419', '8561', '5709', 'u', 'z', '5717', '9711', 'w', 'y', 'm', 'v']
answer:
b, c, f, j, k, l, m, q, r, s, t, u, v, w, x, y, z


question:
['2437', '8065', '6237', 'g', 'o', 'i', 'z', '3503', 'i', '6435', '6153', '4927', 'g', 'l', 'b', 'j', 'c', '2211', '9175', 'e', 'x', 'u', '9405', 'o', '3541', 'i', 'a', 'n']
answer:

a, b, c, e, g, i, j, l, n, o, u, x, z