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:
['4925', 'i', 'q', 'k', '7615', 'r', '7217', 'o', '8097', '9151']
answer:
i, k, o, q, r


question:
['1801', '3713', '117', 'g', 'x', 'd', '607', 'o', 'a', 'a', '4239', 'h', 'e', '6207', 'g', '875', 'e', '1227', 'h', 'q', '8305', 'h', '5919', 'q', 's', 'm', '2553', 'd', '5457', 'k', '5327', 'x', 'e', '8265', 'v', 'a', 's', 'q', '2899', '9927', '6409', '505', 'y']
answer:

a, d, e, g, h, k, m, o, q, s, v, x, y