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:
['e', 'n', 'y', 'f', 'l', 'h', '455', 'y', '591', 'm', '9041', 'b', 'b', 'o', '4215', '5009', 'o', 'a', '4369', 'u', '6911', '4825', 't', 'k', '6063', '2939']
answer:
a, b, e, f, h, k, l, m, n, o, t, u, y


question:
['o', '1099', 'r', '8995', 'o', '2909']
answer:
o, r


question:
['i', 'z', 'y', 'k', 'p', '9785', 'g', '721', 'y', '2769', 't', 'z', 'z', '9785', 'c', '245', '7101', 'q', 'h', 'g', 'z', '689', 'y', 'i', '133', 'l', '3811', '4689', '2839', 'u', '4977', '2363', 'a', 'j', 'z', '8571', 'g', '4659', 'k', '5145', '3547']
answer:

a, c, g, h, i, j, k, l, p, q, t, u, y, z