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:
['u', 'w', '401', 't', 'g', 'h', 'g', '8073', '9597', '1347', '7835', '5007', '977', 'p', '7679', 'b', '4883', '4931', '999', 'r', '1181', 'x', '2063', 'l', 'w', 'i', 'l', 'x', 'i', '9057', '5007', 'w', '743', '1635', 'y', 'f', '9227', 'z', '5227', 'd', '7129', 'k', '7657']
answer:
b, d, f, g, h, i, k, l, p, r, t, u, w, x, y, z


question:
['491', '229', 'g', '6677', '4793', 'h', 'x', 'a', '2333', 'u', 'l', '785', 'p', '7331', '653', '5193', '5415', '8417', 'v']
answer:
a, g, h, l, p, u, v, x


question:
['y', '6619', '3185', '17', 's', '1779', '6559', 'k', 'a', 'e', 't', '2585', 's', '5665', '1837', 'j', '4243', '8837', '8417', 'u', '6843', 'r', 'f', '3113', '4719', '2985', 'b', 'i', '3927', '8777', 'd', '6877', 'o', '9957', '3727', '8911']
answer:

a, b, d, e, f, i, j, k, o, r, s, t, u, y