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', '4021', 'u', 'd', 'j', 'p', 'i', 'z', '3223', 'f', 's', 'l', 'p', 'd', '5031', '1059', '7875', '2097', 'q', 'i', '8813', '2017', 'h', 'l', 'y', '57', '1561', 'f', 'j', 'z', '1901', 'u', 'j', 'x', '6561', '9239', '3333', '8793', '4915', '5821', 'h', 'f', '765', 'x']
answer:
d, f, h, i, j, l, p, q, s, u, x, y, z


question:
['r', '9489', 'e', 'n', '6323', 'd', '3163', '265', '8587', '7891']
answer:
d, e, n, r


question:
['4801', '1107', '7881', 'w', '763', '3861', '4869', '9559', '3969', '5473', '8653', '2269', '7293', 'd', 'w', 'y', 't', 'x']
answer:

d, t, w, x, y