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:
['4123', '1397', '103', 'w', 't', 'j', '233', '7239', 'b', 'n', 't', '6273', 'l', '1167', '8389', '5609', '9029', '7741', 'o', 'p', '6547', '5593', 'd', '8401', 's', '4243', 's', 'u', 'm', '6659', '5691', '2105', '8897']
answer:
b, d, j, l, m, n, o, p, s, t, u, w


question:
['c', 'q', 'e', '5267', 'i', 'k', 't', '7143', 'm', '6407', '6371', 'r', 'l', '6061', 'l', '551', 'u', '5253', 'p', '5121', 'n', '2431', '9551', '4235', 'g', '8263', 'n', 'v', 't', 't', '1787', 'a', '5523', 'p']
answer:

a, c, e, g, i, k, l, m, n, p, q, r, t, u, v