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:
['q', 'g', 's', 'g', 'z', '987', '777']
answer:
g, q, s, z


question:
['2349', 'p', 'a', '435', 'y', 'h', '3249', 'o']
answer:
a, h, o, p, y


question:
['w', '6041', 'i', '2439', 'm', '7643', '8473', 'x', 'u', 'g', 'c', '1795', 'y', 'i', '2551', 'h', 'h', 'r', '4897', 'r', 't', '5781', '391', 'q', 'n', 'p', 't', '4253', '2201', '8891', 'e', 'b', '4283', 't', 'w', '7361']
answer:

b, c, e, g, h, i, m, n, p, q, r, t, u, w, x, y


