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:
['h', 'u', 'y', '7677', '9441', '1769', 'v', '1433', 'l', '7739', 'a', '8305', 'n', 'a', '6711', '3161', 'e', 'u', '993', '2211', '4011', 'q', 'o']
answer:
a, e, h, l, n, o, q, u, v, y


question:
['r', 'q', '3649', 't', '3941', 'z', '3729', 's', 'g', '6905', 'h', 'v', '1085', '6353', 'a', '9395', '5433', 'a', '2565', 'p', 'a', 'h', '1491', 'j', 'b', 'v', 'e']
answer:
a, b, e, g, h, j, p, q, r, s, t, v, z


question:
['3715', '8655', '355', 's', 'r', '8475', 'x', 'c', '4437', 'v', 'd', '8815', 'h', 'f', 'g', '5599', '6007', 'j', 'u', '1741', 'q', 'y', 'u', 'p', '8225', 'j', 'q', 'q', '1465', '6723', 'u', '1307', '1049', 't', 'u', '1885', '6287', '1921']
answer:

c, d, f, g, h, j, p, q, r, s, t, u, v, x, y