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:
['a', 'w', 'm', 'g', 'c', '5475', '7391', 't', '1049', 'p', 'd', '1397', 'k', 'x', 'j', '2525', 'f', '741']
answer:
a, c, d, f, g, j, k, m, p, t, w, x


question:
['5499', 'm', '327', 'h', '5765', '4231', 'y', 'g', 's', '883', '9843', '2751', '8967', 'z', '2301', 'l', 'l', 'k', '7843', '7221', '3643', 'k', '5951', 'r', '9441', '235', '3835', 'l', 'e', 'y', '4061', 'l', '1177']
answer:
e, g, h, k, l, m, r, s, y, z


question:
['3453', '8383', 'e', 't', '8429', '5695', '5227', 'o', '2829', 'f', 'k', 'k', 'f', 'b', 'm', 'm', '4179', '4339', '2501', '4815', 'd', 'r', '5683', 'e', '8109', '7595', 'n', 'n', '1829', 'u', 'u', '9025', 'k', 'y', 'd', '8415', '3163', '3025', 'j', '5697', '3721', 'e', '5121', '2209']
answer:

b, d, e, f, j, k, m, n, o, r, t, u, y