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.

[EX Q]: ['6575', '2057', '2135', '6259', '7741', '4919', '7461', 'v', '401', 'h', 'u', '2391', '2181', 'y', '9273', 'd', 'b', 's', '7993', '9323', 'b', '7015']
[EX A]: b, d, h, s, u, v, y

[EX Q]: ['p', '2923', 'e', 'k', '5433', '605', '5079', 'k', 'p', 'x', '4845', '4099', '6795']
[EX A]: e, k, p, x

[EX Q]: ['5615', '7879', 'k', 'v', '5529', 's', 'a', 'a', '477', 'u', 'm', '5623', '3837', 'q', '6807', '7545', 'g', '4299', '1667', 'm', '979', 'w', 'z', 'h', 'z', 'p', 'f', 'v']
[EX A]:
a, f, g, h, k, m, p, q, s, u, v, w, z