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:
['7917', '2295', 'q', 'v', '9373', 'w', 'n', 'q', '5803', 'g', 'k', 'm', '2167', 'k', '6425', 'x', 'g', '341', 't', 'u', '8829', 'h', '4333']
answer:
g, h, k, m, n, q, t, u, v, w, x


question:
['6599', 'f', 'c', '661', 'q', 'e', '1951', 'f', 'f', 'a', 'd', '9521', '853', 'n', 'w', '6451', '5549', 'k', 't', 'l', 'z', 'm', 'k', '567']
answer:
a, c, d, e, f, k, l, m, n, q, t, w, z


question:
['5741', '3385', 'n', '1345', 'u']
answer:

n, u