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

Answer: e, x, z


Question: ['s', 'u']

Answer: s, u


Question: ['z', '611', 'x', 't', '2705', '2427', 'c', 'y', '5677', '4359', '5187', 'm', 'e', 'p', '7555', '6067', 'r', '377', 'k', '131', 'n', '9915', '9277']

Answer:
c, e, k, m, n, p, r, t, x, y, z