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]: ['q', 'g', 's', 'g', 'z', '987', '777']
[A]: g, q, s, z


[Q]: ['o', '1099', 'r', '8995', 'o', '2909']
[A]: o, r


[Q]: ['529', 'x', 'b', '7113', 'a', '7847', 'f', '7001', 'k', '9349', 'b', '267', '6289', '3979', 'c', '3621', '8995', 'x', '5111', '1005', '5955', 's', 'y', '3465', 'c']
[A]:
a, b, c, f, k, s, x, y