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: ['c', '7039', 'g', '1899', 'r', '507', 'c', '2587', '3865', '1729', '3927', 'r', '3535', '2791', 'm', 'l', 'r']

Answer: c, g, l, m, r


Question: ['421', '3513', '1675', '175', 'e', '7233', '8297', '175', 'o', 'e', '9311', '9917', '497', '797', 'u', 'k', '3725', '1513', '1569', 'y', 'k', 'o', '9825', '5137', 't', '575', '6379', 'n', 'y', '227', 'f', '4381', '5221', 'g', 'j', 'f', '8279', 'b', '6895', 'q', 'r', '3869', 'e', 'b']

Answer:
b, e, f, g, j, k, n, o, q, r, t, u, y