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:
['395', '8309', 'v', 'r', 'x', 'j', 'l', 'b', 'c', 'c', '3123', 't', 'a']
answer:
a, b, c, j, l, r, t, v, x


question:
['8821', '9833', 'l']
answer:
l


question:
['s', '7065', '8109', 't', '791', 'l', 'a', 'j', '4941', '9461', 'h', '3655', 'i', '1083', '2713', 'm', 'b', '7901', '895', '8015']
answer:

a, b, h, i, j, l, m, s, t