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:
['l', 'o', 's', '7411', '7847', '2557', '1977', '2863', '2325', '4177', '4183', '4241', '1005', '1137', '1371', 'v', 'p', 'a', '2453', 'l', '6315', 'l', '6463', 'n', '7645', '9669', '5411', '1631', '5995', 'z', '227']
answer:
a, l, n, o, p, s, v, z


question:
['3117', 'i', 'd', '7537', 'i', 'q', '4649', '7263', '3655', 'd', 'x', '8569', 'g', '2389', '3933', '7099', '563', '3055', '9941', 'm', 'c', '3529', '3577', 'x', 's', 's', '6153', '1731', '9679', 'f', '8839', '5183', '5', '6433']
answer:
c, d, f, g, i, m, q, s, x


question:
['d', 'h', 'k', 'r', 'o', '5641', 'j', 'k', 'i', '9359', '689', 'u', 'n', '1235', '1389', '9171', '7869', '2577', '7063', 'a', '663', '337', 'm', '7635', '1859', '9781', 'c', '947', '963', 'q', '2839', '5913', 'k', '9327', 'g', '5959', '3861']
answer:

a, c, d, g, h, i, j, k, m, n, o, q, r, u