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.

[EX Q]: ['w', 'n', '729', '2491', 'n', 'x', '915', '1869', 'z', '8491', '9947', '561', '829', 'n', 't', 'i']
[EX A]: i, n, t, w, x, z

[EX Q]: ['x', 'b', '1467', 'y', '2101', 'y', 'm', '2745', 'z', '429', '7523', 'e', 'f']
[EX A]: b, e, f, m, x, y, z

[EX Q]: ['u', 'p', 'b', '7613', 'c', 'y', 'i', 'c', '3113', 'd', '3971', 'y', '4227', 'y', 'm', '8755']
[EX A]:
b, c, d, i, m, p, u, y