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:
['6463', '871', '5781', '283', '9653', 'f', '9661', '3365', '2889', '5499']
answer:
f


question:
['r', 'j', '437', 'b', '5223', 'n', 'v', '437', 'd', '8285', 'k', 'j', 'r', 'p', 'n', 'e', 'n', 'j', 'o', '2651', 'j', '6365', 'q', 'q', '2159', 'g', '3641', '7727', 'c', '1197', 's', 't', 'n']
answer:
b, c, d, e, g, j, k, n, o, p, q, r, s, t, v


question:
['h', '4187', '8071', 'g', '1443', '3263', '7343', '6069', 'm', '1913', '6547', '9023', 'w', 'b', '8739', '5241', 'h', 'd', '9557', '5219', '7103', 'r', '2383', '7835', '3949', 'm', 'n', '5029', '9187', 'i', '4731', 'q', 'o']
answer:

b, d, g, h, i, m, n, o, q, r, w