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: ['a', 'a', 'b']

Answer: a, b


Question: ['k', 'z', '303', 'a', 'f', 'q', 'i', '1475', '3453', 'd', 'w', '4037', 'z', 'h', 'k', '3547', '1561']

Answer: a, d, f, h, i, k, q, w, z


Question: ['j', '6621', 'h', 'k', '4957', '3579', 'c', '9407', '1825', '9145', 'n', 'l', 'x', 's', '7443', '1501', '1239', '9219', 'l', '303', 'd', 'j', 'w', '3803', 'k', 'l', '2609', '6143', 'y', '4789', '8155', '4211', 'm', '5771', 'u']

Answer:
c, d, h, j, k, l, m, n, s, u, w, x, y