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:
['f', '6817', 'f', 'd', '3835', '3051', 'u', 'l', '7679', 'b', '3931', '1441', 'q', '8675', 's', '5487', 'y', '2279', 'x', 'y', '9513', '2875', '1771', '879', '2927', '3469', 'v', 't', 'k', '9991', '2565', '7345', '973', 'w', 'i', '6105']
answer:
b, d, f, i, k, l, q, s, t, u, v, w, x, y


question:
['7997', 'm']
answer:
m


question:
['7745', '8281', '8085', '9587', '2633', '1529', '7911', 'k', '9865', '3147', '6997', 'i', '4687', '8483', 't', 's', 'j', 'l', 'e', 'x', 'z', '1365', '4671', 'e', 't', '2105', 'w', '4485', 'v', '3815', '8395', '5617', '5625', 'f', '3715', 'f', '8693', '197', '9239']
answer:

e, f, i, j, k, l, s, t, v, w, x, z