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:
['k', '1995', 'b', '2581', 'x', '2639', 'i', '6761', '2701', 'd', '6993', '9375', 'r', 'm', '249', '8115', '8179', 't', '4901', 'i', '6197', '2809', 'e', 's', 'j', '4261', 'f', '6649', '7527', '3839', '5651', '9287', 'n', '2505', 's', 'q', '2825', 'g']
answer:
b, d, e, f, g, i, j, k, m, n, q, r, s, t, x


question:
['a', 'y', '7401', 'e', 'l', '4351', 'p', '5673', 'k', '333', 'o', 'd', 'e', 'j', 'e', '9569', '1795', 'r', 'z', '6059', '4399', '2927', 'n', '9387', '9317', 'b', 'c', 'e']
answer:
a, b, c, d, e, j, k, l, n, o, p, r, y, z


question:
['y', '1767', '1459', 'v', '1723', '4813', '1051', 'i', 't', '2773', '8513', 'c', '6355', 'q', 'c', 'h', '135', '3325', '3957', '6111', '1451', 't', '2683', '8041', '4345', 'c', '2825', 's', 'q', 'i', 'z', 'r', 'a', '7707', 'f', '9781', 'n']
answer:

a, c, f, h, i, n, q, r, s, t, v, y, z