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:
['491', '229', 'g', '6677', '4793', 'h', 'x', 'a', '2333', 'u', 'l', '785', 'p', '7331', '653', '5193', '5415', '8417', 'v']
answer:
a, g, h, l, p, u, v, x


question:
['m', '6761']
answer:
m


question:
['7013', '3127', '1321', '4631', '8615', '8579', 'n', 'o', 'j', '7185', '9905', '3367', '3213']
answer:

j, n, o