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:
['6175', '9441', '7127', '5979', 's', '1367', 'e', 'm', '7083', '1787', '8375', '2851', '3475', 'r', '697', 'g', 'z', 'm', '4207', 'c', '7971', 'z', '9339', 'd', 's', '3507', '9003', 'i', 'y', 'w', 'j', 'i']
answer:
c, d, e, g, i, j, m, r, s, w, y, z


question:
['2819', 'k', 'u', 'a', '4575', 'a', 't', 'a', 'f', '1507', '415', 'w', 'o', 'o']
answer:
a, f, k, o, t, u, w


question:
['u', '4073', 'r', '603', 'w', 'u', '3925', 'g', '1295', 'a', '4635', '8825', 'w', 'u', 'f']
answer:

a, f, g, r, u, w