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:
['1593', '8165', 'q', '6689', 'b', 'r', '373', 'g', '6505', '415', '495', 'j', 'j', 'f']
answer:
b, f, g, j, q, r


question:
['1429', '7273']
answer:
-1


question:
['h', '4589', '9151', 'p', '387', 'u', '3017', 'r', 'l', 'f', '793', '7807', 'a', 'q', 'q', '9773', 'a', '3497', 'k', 'b', '3739', '1589', 'o', 'x', '9775', 'j', '4253', '4867']
answer:

a, b, f, h, j, k, l, o, p, q, r, u, x