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:
['f', '3409', 'i', '4147', '1745', '6007', 'l', 'd', 'i']
answer:
d, f, i, l


question:
['e', 'z', '5199', 'x']
answer:
e, x, z


question:
['9687', '3485', '4171', 'n', 'v', 'w', 'i', 'f', 'i', 'z', 'q', 'a', 'm', 'a', 'c', 'c', 'p', '307', 'x', '1357']
answer:

a, c, f, i, m, n, p, q, v, w, x, z