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:
['n', 't', '2901', '9697', 'a', 'j', 'x', 'a', '4437', '2255', '2177', 's', '3173', 'j', 't', '5713', '4091', '4253', '5553', 'i', '4533', 'i', 'e', '6899', 's', '3541', '2139', '2705', 'm', 'u']
answer:
a, e, i, j, m, n, s, t, u, x


question:
['5161', 'v', 'y', '6005', 'y', 'l', '5451', 'z', 'j', 'd', '4597', '9319', '1241', 'g', 'f', 'b', 'g', '683', '763', 'm']
answer:
b, d, f, g, j, l, m, v, y, z


question:
['8485', '9305', '3941', '353', 'n', '749', '3019', '3245', '4021', 'v', '4457', '2403', 'h', '5947', 'a', 'y', '279', 'p', 'v', '2577', '1159', 'v', 'p', '3721', 'm', 'r', '591', 'k', 'j', 'z', 'o', '5979', 'k']
answer:

a, h, j, k, m, n, o, p, r, v, y, z