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:
['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:
['p', '6123', '6961', 't', 'p', 'h', '9035', 'r', '6341', 'x', '3635', '5885', 't', '3543', '9567', '1787', 'o', '2991', 'k', '3441', '4091', 'a', 'r', '423', '9383', '7147', 'h', '663', 'd']
answer:
a, d, h, k, o, p, r, t, x


question:
['2059', 'f', 'a', 'w', '6997', '5857', '3023', '4395', 'b', '3737', '9697', 'x', '6041', 'l', 'i', 'q', 'q', 'p', '4955']
answer:

a, b, f, i, l, p, q, w, x