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:
['1367', 'h', '4153', '1587', 'h', 'b', 'n', 'u', 'n']
answer:
b, h, n, u


question:
['2775', '7507', 'c', '4417', '3449', 'y', 'z', 'e', 'f', '9515', '8555', '7269', '8353', '4239', '4347', '4479', '8645', '9925', 'o', 'h', 'o', '8641', 'y', '3251', '1191', 't', 'x', 'z', '7203', 'b', 'b', '7545', '7283', 'z', 'y', '8127', 'x', 'l', '6251', 'y']
answer:
b, c, e, f, h, l, o, t, x, y, z


question:
['h', 'n', 't', 'u', '1815', '1039', '8523', 'k', '9793', '675', '4853', '7787', 'e', 'j', '8031', '5971', '5203', 'k', 'x', '1301', 'f', 'f']
answer:

e, f, h, j, k, n, t, u, x