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.
--------
Question: ['d', '1625']

Answer: d


Question: ['a', 'y', '7401', 'e', 'l', '4351', 'p', '5673', 'k', '333', 'o', 'd', 'e', 'j', 'e', '9569', '1795', 'r', 'z', '6059', '4399', '2927', 'n', '9387', '9317', 'b', 'c', 'e']

Answer: a, b, c, d, e, j, k, l, n, o, p, r, y, z


Question: ['673', '5977', 's', 'd', 'b', 't', '4893', 'k', 'a', '6133', '8707', '9145', 'r', 'i', '8621', 'h']

Answer:
a, b, d, h, i, k, r, s, t