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:
['n', '6615', 'r', 'q', '3803', '4641', '9775', '7719', 'n', '6571', '2723', '6919', 'e', 'f', '1919', '6963', '2581', 'y', '713', 'w', 'w', 'w', 'l', 's', '3993', '9563', '9365', '9277', '103', '2737', 'y', '6005', '9763', 'p', '261']
answer:
e, f, l, n, p, q, r, s, w, y


question:
['w', 'n', '729', '2491', 'n', 'x', '915', '1869', 'z', '8491', '9947', '561', '829', 'n', 't', 'i']
answer:
i, n, t, w, x, z


question:
['w', 'o', 'b', '7277', 'i', 'e', '4621', 'g', '9357', '2643', '5893', '4847', 'a', '2809', 'l', '8139', 'c', '4679', '4461', 'k', '5031', '5605', '7189', '6637', 's', '5559']
answer:

a, b, c, e, g, i, k, l, o, s, w


