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

Answer: c, g, l, m, r


Question: ['e', 'z', '5199', 'x']

Answer: e, x, z


Question: ['o', 'j', '4229', '4955', 'i', 'b', '25', '783', 'q']

Answer:
b, i, j, o, q