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:
['1945', 't', '4477', '4439', '6569', '2021', 'y', 't', '2725', '8947', '6921', '1373', '8107', 'g', 'c', 'w', 'x', 'b', '9117', 'k', '6567', '5073', '2307', 'e', 'b', '7405', 'e', 'x', '1419', 'd', 'o', 'n', 'a', '2647', 'z', '1459', 'n', '6137', 'u', 'b', 'q', '4459']
answer:
a, b, c, d, e, g, k, n, o, q, t, u, w, x, y, z


question:
['d', 'p', 'k', '9679', 'x', 'j', '7481', '1815', 't', 'w', '6513', 'j', '5079', '5219', 'p', '9545', 'a', '1931', '9973', '8125', '5169', '2791', 't', 'd', '2057', 'e', 'x', 'y', '7409', 'u']
answer:
a, d, e, j, k, p, t, u, w, x, y


question:
['8859', '667', '5581', '5063', 'o', '7029', '6571', 'x', '4343', 't', '1471', 'i', 'f', '1263', '8319', '4629', 't', 'j', 'd', '495', 'u', 's', 'u', '911', '2843', '1383', '6393', '3773', '9473', 'v', '3839']
answer:

d, f, i, j, o, s, t, u, v, x