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:
['1801', 'q', '5101', '8863', '2309', 'p', '8789', '9529', '6135', '5523', 'f', '8889', '7639', 'k', '263', '5751', '5529', 'g', '1451', '4143', 'e', '6987']
answer:
e, f, g, k, p, q


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:
['l', 'o', '4829', 'b', 'l', '7575', 'n', '181', 'v', 'n', 'a', '5027', '4365', '6369', 'f', 's', '8039', 'r', '9743', '3461', '2625', '7409', 'p', '2269', '3821', '4667']
answer:

a, b, f, l, n, o, p, r, s, v