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:
['2161', '8009', '3057', 'r', '3897', 'd', 'j', '2727', 'b', '3231', 'i', '9227', '393', '5799']
answer:
b, d, i, j, r


question:
['2313', '2073', 'd', 'e', 'o', '793', '4999', 'f', 'c', '4473', '4519', 'u', 'n', 'k', '69', '475', 'a', 'j', 'q', 'x', '5869', '9523', 'z', 'v', '9265', '5989', 'p', 'm', 'g', 'y', 'b']
answer:
a, b, c, d, e, f, g, j, k, m, n, o, p, q, u, v, x, y, z


question:
['x', '4481', 'l', '2305', 'x', '4903', 'n', 'j', '9369', '365', 'r', '9993', '1571', '5107', '979', '1271', 'n', '2097', 'v', 'h', 'm', 'd']
answer:

d, h, j, l, m, n, r, v, x