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:
['5611', 'x', 't', 'p', '5711', '7079', '5251', '429', 'z', 'u', '8721', '9321', '79', 'i', '189', '3605', 'k', '445', 'r', 'k', 'o', '2189', '8521', '8849', '2651', 'm', '4149', '1577', '3085', '5275', '6413', '5265', '6089', 'r', 'f', '5013']
answer:
f, i, k, m, o, p, r, t, u, x, z


question:
['s', 'w', '8949', '4025']
answer:
s, w


question:
['s', '3447', '4539', 'o', 'h', '2989', 'm', '6249', 'p', 'd', '281', 'd', '9977', '83', '3701', '5933', '7243', '7683', '1107', '7331', 'e', 'w', 'w', 'r', 'u', '6767', 't', '539', 'y', '2727', 'f', 'u', 'd', '8609', 't', 's', '9065', 'b', 'r', 'n', 'd']
answer:

b, d, e, f, h, m, n, o, p, r, s, t, u, w, y