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:
['h', '6865', '4019', '8571', 'y', '5575', '7835', '9537', 'n', '875', 't', 'a', 's', '2769', 'p', '1607', 'n', '4087', '961', '7869', '5085', '2131', '4867', 'j', 'h', 'y', '3105', '6609', 's', 'l', '3399', '5013']
answer:
a, h, j, l, n, p, s, t, y


question:
['s', 'j', '6779', '1535', 'd', 'e', 'u', '3023', '241', '9115', 'h', '8003', '3755', 'q', 'm', '2725', 'x', 'y', 'n', 'm', 'j']
answer:
d, e, h, j, m, n, q, s, u, x, y


question:
['b', 'd', 'a', '4129', 'w', 'h', 's', 'v', 'o', '3139', 'x', '4167', '2677', '7029', 't', 'd', '5817', 'e', 'i', '4641', 'd', '2155', 'r', 'c', 'm', '5311', 'n', '7397', '6925', '3829', '1551', 'f', '1765', '65', '4825', '5337', '4183', 'd', '5853', 'm', 'p', '8677', 'f']
answer:

a, b, c, d, e, f, h, i, m, n, o, p, r, s, t, v, w, x