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: ['6955', '721', '2763', '8121', '9109', '6341', 'p', 't', 'x', '6963', '1137', 'z', 'u', '1949', '7029', 't', '9539', 'a', 'u', '1873']
Example Output: a, p, t, u, x, z

Example Input: ['u', '4731', 'l', 'p', '1997', '601', 'n', 'l', 'p', '211', '7355', '6537', 'w', 'x', '1741', '8145', '3689', 'm', 'y', '6945']
Example Output: l, m, n, p, u, w, x, y

Example Input: ['a', 'o', 'r', 'h', '469', '2483', 'e', 'z', '3717', '8681', 'l', '219', 'd', 'b', '9725', '7365', '5373', '3843', 'f', 'a', 'h', 's', '3517']
Example Output:
a, b, d, e, f, h, l, o, r, s, z