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: ['i', 's']

Answer: i, s


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: ['r', 'i', 'j', 'c', 'u', '1675', 'r', 'n', '5781', '8453', '9439', 'z', 'l', 'p', '9813', 'g', 'c', '459', '613', '8499', '3103', 'e', '2113', '7549', 'w', 'a', 'z', '2451', 'y']

Answer:
a, c, e, g, i, j, l, n, p, r, u, w, y, z