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:
['u', '4021', 'u', 'd', 'j', 'p', 'i', 'z', '3223', 'f', 's', 'l', 'p', 'd', '5031', '1059', '7875', '2097', 'q', 'i', '8813', '2017', 'h', 'l', 'y', '57', '1561', 'f', 'j', 'z', '1901', 'u', 'j', 'x', '6561', '9239', '3333', '8793', '4915', '5821', 'h', 'f', '765', 'x']
answer:
d, f, h, i, j, l, p, q, s, u, x, y, z


question:
['2633', 'd', 'r', '8083', 'f', 'd', '5121', '8651', 'o', 'b', '811', '7551', 'x', 'p', 'm', 'v', 'm', '7833', '1959', 'y', 'p', '779', '1889']
answer:
b, d, f, m, o, p, r, v, x, y


question:
['s', 'g', '3539', 'n', 'q', '65', 'v', '5889', 'p', '8093', '4757', 's', '9887', 'b', 'n', 'e', '9803', 'n', '6899', '6361', '7205', '4821']
answer:

b, e, g, n, p, q, s, v