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:
['3019', 'g', 'q', 'u', '611', 'z', '3671', '8119', '1679', 'h', '2631', '655', 'k', '2837', 'e', 'f', 'e', 'f']
answer:
e, f, g, h, k, q, u, z


question:
['7065', 'f', 'k', 'i', 'd', '8291', 'z', 'e', 'q', '5345', 'h', '3397', 's', '5355', 's', '9033', 'e', '5241', '5285', 'm', 'h', 'i', 'n', '6471', '3365', 'f', 'r', '6145', 't', '4869']
answer:
d, e, f, h, i, k, m, n, q, r, s, t, z


question:
['z', '9425', 'o', '4401', '7221', 'f', '8165', 'z', 'i', '9647', 'e', '4619', 'e', '9783', 'a', 'c', 'q', 't', '8055', 'm', 'k', 'y']
answer:

a, c, e, f, i, k, m, o, q, t, y, z