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:
['w', '8777', 'y', 'e', '8015', 't', 'w', '53', '9149', 'e', 'k', '1837', 'b', 's', '4007', '4905']
answer:
b, e, k, s, t, w, y


question:
['z', 'h', '2065', '6773', 'v', '151', '8957', 't', 'l', 'j', '7867', 'v', '799', '9009', '4317', 'm', '6921', 'r', '1245', '5637', 'x', '4465', 'f', 'y', '3549', 'e', 'f', 'm', 't', '6281', '4241', '3415', 'z', 'g']
answer:
e, f, g, h, j, l, m, r, t, v, x, y, z


question:
['4777', 'b', '6415', 'l', 'v', 'f', '969', '6909', 'l', '7153', 'r', 'x', '4043', 'z', 'v']
answer:

b, f, l, r, v, x, z