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:
['a', 'p', 'y', 'l', 'l']
answer:
a, l, p, y


question:
['8879', 'x', '1383', '4925', '2867', 'j', 't', 'e', 'w', 'p', 't', 'w', 'l', '7447', '1877', '7747', 'k', 'b', 'x', '8565', 'q', '8575', '5711', '2949', '5637', '2197', '4905']
answer:
b, e, j, k, l, p, q, t, w, x


question:
['2543', '3967', '3039', '7529', '5923', 'r', 't', 'j', '3101', 'v', 'k', 't', 'x', '199', '8835', '1569', '1533', 'w', '5701', '5989']
answer:

j, k, r, t, v, w, x