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:
['u', 'i', '1185', '3795', '5417', 'k', 'b', '2629', '2635', 'z']
answer:
b, i, k, u, z


question:
['w', '6291', '3939', '9569', 'u', '1635', '3359', '8335', 'n', '2799', '7359', 'k', 'm', '2817']
answer:
k, m, n, u, w


question:
['m', 'y', 'd', '651', '6281', '1881', '3709', 'x', 'z', '4919', '9141', 'v', '5847', '7239', 't']
answer:

d, m, t, v, x, y, z