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:
['2453', 'r', 'd', '8499', 't', 's', 'h', 'a', 'm', '9271', 'g', '2599', '6209', 'o', 'i', '4069', 't', '6793', '7679', '6643', '7359', 'm', 'f', 'w', '775', '3347', '6161', '9745', 'i']
answer:
a, d, f, g, h, i, m, o, r, s, t, w


question:
['w', 'g', '1649', 'a', '2115', '6763', 'r', 't', 'l', 's', 'y', '5659', 'a', 'b']
answer:
a, b, g, l, r, s, t, w, y


question:
['2747', '6117', 'j', '2763', '9195', 'x', 'r', 'e', '4037', 'f', '9485', 'z', '4381', 'e', 'j', '7015', 'a', '8743', 'u', '7677', 'h', '1629', '6191']
answer:

a, e, f, h, j, r, u, x, z