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]: ['9117', '1153', 'f', 'b', '9979']
[EX A]: b, f

[EX Q]: ['d', '2359', '6571', 'c', 'n', 'u', '9513', '9321', '1689', 'b', '969', '1823', 'e', 'b', '9147', 's', '1811', 'k', '5443', '8699', '5483', 'v', 'w', 'n', '1215']
[EX A]: b, c, d, e, k, n, s, u, v, w

[EX Q]: ['5237', '8081', '8229', '1847', '5747', 'n', '4489', '2245', '6799', 'r', '6513', '5061', 'u', '681', 'i']
[EX A]:
i, n, r, u