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:
['2705', 'n', 'r', '8259', '6839', '3239', 'w', 'z', '2611', '2957', '2303', '6315', '7801', 'c', 'w', 'm', '5049', '6465', '599', 'h', 'q', '7559', 'n', '9917', 'v', 'l', '643', '6415', '3587', 'c', '917', '4435', 'p', 'a', '317']
answer:
a, c, h, l, m, n, p, q, r, v, w, z


question:
['8489', 'h']
answer:
h


question:
['4383', 'z', '6143', 'j', 'b', '1707', 'b', '331', '1033', '5249', '5897', '8479', 'h', '3617', '387', 'o', 'n', 'q', '4307', '6793', 'i', 'v', 'a']
answer:

a, b, h, i, j, n, o, q, v, z