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:
['9025', '3259', '4863', 'u', '6443', '9931', '627', 'x']
answer:
u, x


question:
['7441', '7967', '2011', '1383', 'i', '3623', 'b', 'y', 'e', '1593', 'r', 'a', 'd', 'b', '6159', '3931', '989', '435', 'o', 'y', 'j', 'w', '7669', 'y', '5781', 'u', '531', '7467', '3971', '8139', 'w', 'a', '5113', '9461', '8377', '7431', '6975', '6055', '7307', 'v']
answer:
a, b, d, e, i, j, o, r, u, v, w, y


question:
['3055', 'v', 'm', 'a', '905', '6307', 'f', 'k', 'k', '1799', '561', 'w', 'n', 'g', 'y', '6169', '325', 'm', 'a', 'm', '9555', '6879', 'x', '2191', 'v', '7959', '1167', '7973', '7843', 'a', 'z', 'g', 'i', 't', '2457', '8019', 'w', 'q', '6363', 's', '7909']
answer:

a, f, g, i, k, m, n, q, s, t, v, w, x, y, z