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:
['a', '7599', 'i', '9455', '3955', '2015', 'j', '7345', 'x', 't', 'c', '1317', '9155', '6383', '7793', 'n', '5581', 'v', '3485', 'n', 'r']
answer:
a, c, i, j, n, r, t, v, x


question:
['j', '917', 'w', 't', '8873', '1431', '8059', '7041']
answer:
j, t, w


question:
['q', 'n', '3725', 'q', 'a', 'f', 'a', 'o', '2297', '5819', '79', '8925', '3205', 'f', '5617', 'i', '5031', 'h', '733', 'w', 'i', '2635', 'm']
answer:

a, f, h, i, m, n, o, q, w