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:
['u', 'i', '1185', '3795', '5417', 'k', 'b', '2629', '2635', 'z']
answer:
b, i, k, u, z


question:
['1063', 'f', 'm', 'i', 'x', 'i', 'd']
answer:
d, f, i, m, x


question:
['4721', '1043', 'h', '8045', 'h', 'k', 's', '6293', '7299', 'w', '7329', '4689', '343', 'n', 'g', '5765', 'i', 'a', 'c', 's', 'j', 'x', '7537', 'h', '8215', '7903', 'v', 't']
answer:

a, c, g, h, i, j, k, n, s, t, v, w, x