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:
['8821', '9833', 'l']
answer:
l


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:
['x', '8641', '4869', '8261', '957', '4347', 'm', '4749', '8441', '1817', 'c', '4117', '7683', '1789', 't', 's', 'r', 'o', 'l', 'd', 'n', '9209', '7395', '3607', 'f', '4603', 'g', 'g', '3809', 'y', '6093', 'n', 'e', 'k', '4593', 'y', '5891', 's', '5443', 'q', 'q', 'r', 'c', '585', '2699']
answer:

c, d, e, f, g, k, l, m, n, o, q, r, s, t, x, y