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.

Example Input: ['4641', '2881', 'c', '4827']
Example Output: c

Example Input: ['r', 's', '2471', 'n', '635', 'k', '3551', '7041', '8765', '1221', '8439', '7773', '6471', 'u', 'p', '2093', '6479', '1435', '6881', 'a', 'y', 'm', 'r', '1627', 'w', 'k', 'b', '3095', '9059', '285', 'y', 'a', 'm', 'x', '637', 'i', '3407', 'e', 'e']
Example Output: a, b, e, i, k, m, n, p, r, s, u, w, x, y

Example Input: ['6281', '5189', '7821', '3179', '3679', '4391', '3313', '6673', 'w', '5631', 't', 'h', 'e', 'h', 'r', '9787', 'r']
Example Output:
e, h, r, t, w