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:
['9403', '9881', '8391', 't', '1793', 'w', 'x', 'y', '6383', 'j', 'r', '5323', 'r', 'l', 'e', 'u', '7193', '2309', '837', 'z', 'w', 'n', '4427', '8269', '6333', 'a', 'p', '1933', '8497', '2665', '1349', '6807', '9009', 'b']
answer:
a, b, e, j, l, n, p, r, t, u, w, x, y, z


question:
['w', 'a', 'm', 'd', '409', 'm', 'v', 's', '7801', 'l', '8551', 'k', '867', 'n', '7731', 'z', '3773', '9137', 'v', 's', 'p', 'p', 'f', 'z', 'g', 'q', 'g', '877', '697', '2057', '8389', '2399', '5263', '2761', '9841', '1781', 'l', '8023']
answer:
a, d, f, g, k, l, m, n, p, q, s, v, w, z


question:
['9397', '4675', '3987', '4573', '7569', 'z', 'u', 'j', 'y', '9947', '8283', '8985', 'n', 'z', '5577', '3169', 'o', 'c', 'x', 'k', '189', '5615', 'y', '999', '5553', 'o', 'n', 'y', '7715', 'f', 'h', '1155', 'a']
answer:

a, c, f, h, j, k, n, o, u, x, y, z