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:
['f', 'a', 'r', '4009', 'k', 'a', 'g', '7725', 'v', 'b', '6705', 'a', '6583', '3159', 'c', 'w', 'x', 'h', '7625', 'p', 'y', '5645', 'k', 'r', 'j', '4175', 'r', '3103', '8631', '5999', 'p', 'g', 'h']
answer:
a, b, c, f, g, h, j, k, p, r, v, w, x, y


question:
['8829', 'm', '5369', 'q', '5737', '7799', '5705', 'p', 'w', '1983', '4849', 'h', '6771', 'p', 'y', '1071', 'u', '6401', '7723', 'p']
answer:
h, m, p, q, u, w, y


question:
['1621', '5559', '5239', '9781', '8071', 'g', '2091', '6121', 'i', '2729', 'e', '137', '8489', 'k', '4407', '1653', 'w', '1853', '7095', 'b', '5831', '6941', '1823', 'f', '9679', 'v', 'f', '9389', 'c', 'n', '6297', '5759']
answer:

b, c, e, f, g, i, k, n, v, w