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: ['5489', 'f', '6833', 's', 'c', '6575', 'w', '2957', '8465', 'v', 'h', '2119', '7731', 'e', '5367', 'e', '3357', 'p', '7565', 'n', 'x', 'n', 'f', '1075', '5941', '6505', 'j', 'p', '2853', 'l', 'q', '4727', 's']

Answer: c, e, f, h, j, l, n, p, q, s, v, w, x


Question: ['4787', 'c', '1727', '9863', '8147', '3931', 'b', '1133', '3023', '7427', '7837', 'n', '7921', 'o', 'c', '3973', '1949', 'x', 'g', 'b', 'd', '8559', '8661', '4465', 'z', '369', 'q', 'e', 'y', '8629', '7665', 'i', 'r', 'n', 'z', '9115', '1393', '4899']

Answer: b, c, d, e, g, i, n, o, q, r, x, y, z


Question: ['3967', 'd', 's', '6359', 'b', '915', '3989', 'u', 'z', 'r', 'u', 'g', 'm', 'm', '2947', 'n', 'f', 'l', 'i', '1959', 'g', '9077', 'b', 'i', '8919', '8187', '2155', '5431', 'b', '1487', 'x', '8631', 'y', '9971', 'h', '2793']

Answer:
b, d, f, g, h, i, l, m, n, r, s, u, x, y, z