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.

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

A: l, m, n, p, u, w, x, y
****
Q: ['8975', '7199']

A: -1
****
Q: ['5911', '85', 'k', '7299', '373', 'n', 'b', '1685', '6935', 'h', '5263', '3301', '7237', 't', '4641', 'm', '4771', 'm', 's', 'q', 'x', 'i', 'y', '8563', '5597', '2517']

A:
b, h, i, k, m, n, q, s, t, x, y
****