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.

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

A: a, b
****
Q: ['w', 'n', '729', '2491', 'n', 'x', '915', '1869', 'z', '8491', '9947', '561', '829', 'n', 't', 'i']

A: i, n, t, w, x, z
****
Q: ['u', '7657', 'q', 'l', 'm', 'o', '8625', '4535', '3037', '1161', 'd', '7557', 'g', '2089', 'z', 'i', '2147', 'o', '2859', '5355', 'y', 'q', 'h', '6997', 'h', '5469', '2143', '1923', '5507', 'r', 'w', 'a', '1405', '8737', 't', '9129', 'l', '4153', '2125', 'l', 'w', 'i', '5943', 'u', '7661']

A:
a, d, g, h, i, l, m, o, q, r, t, u, w, y, z
****