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:
['1595', '2915', 'o', 't', 'c', 'h', '3969', '5407']
answer:
c, h, o, t


question:
['r', 'y', 'c', '3211', '9245', '8459', '8521', '5781', 'w', 's', 'd', '5299', 'a', 'y', 'g', 'm', '6435', '8605', 'e', 'h', '6871', 's', '387', 'l', '5829', 'e', 'd', '9545', '2945', 'k', 'v', 't', '8449', '2199', 'm', '2599', '1489', '6623', 'x', 'l']
answer:
a, c, d, e, g, h, k, l, m, r, s, t, v, w, x, y


question:
['5697', 'v', 'k', '7361', '2379', '207', '5837', 'k', 'i', '9819', '455', 'w', '5803']
answer:

i, k, v, w