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: ['57', 'j', 'n', '877', 'u', 'w', 'j', 'f', '8977', 'h', '469', '9417']

A: f, h, j, n, u, w
****
Q: ['c', 'e', '6509', '1295', 'u', '5445', '1731', '3049']

A: c, e, u
****
Q: ['a', '137', 'j', 'g', '3807', '3981', 'u', '3787', '7819', 'l', 'c', 'w']

A:
a, c, g, j, l, u, w
****