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:
['o', 'z', 'h', '3965', 'n', '3009', '173', '997', '3987', '5799', '2331', 'p', 'x', '897', '8213', '451', 'u', 't', 't', '9917', '4501', 't', 'c', 'i', 'w', 'w', 'u', '2977', 't', 'b', '4161', '9281', 'w', 'f', '3137', '5745', 'e', '673', '6363', 'h', 'q', 'x', 'm', '9505']
answer:
b, c, e, f, h, i, m, n, o, p, q, t, u, w, x, z


question:
['699', 'd', '6027', 'j', 'e', 'c', 't', '9983', '5471', '2649', 't', '2631', 'r', 'h', '293', 'j', '8699', 'p', 'k', '5433']
answer:
c, d, e, h, j, k, p, r, t


question:
['2021', '5739']
answer:

-1