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:
['565', 'i', '615', '3047', 'm', '195', '7547', '3003', '9213', '9063', 'c', '5099', 'v', '5003', '9053']
answer:
c, i, m, v


question:
['w', '1367', '5389', '9515']
answer:
w


question:
['8211', '6843', '2373', '8891', '2067', 'r', '6315', '1375', 'x', '491', 'p', 'y', 'f', 'y', 'q', '7595', '307', 'x', '6423', 'l', '1347', '2929', 'u', 'g', '993', 'n']
answer:

f, g, l, n, p, q, r, u, x, y