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.
One example: ['8129', 'a', '4245', 'y', 'm', 'a']
Solution is here: a, m, y
Explanation: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.

Now, solve this: ['1621', '5559', '5239', '9781', '8071', 'g', '2091', '6121', 'i', '2729', 'e', '137', '8489', 'k', '4407', '1653', 'w', '1853', '7095', 'b', '5831', '6941', '1823', 'f', '9679', 'v', 'f', '9389', 'c', 'n', '6297', '5759']
Solution:
b, c, e, f, g, i, k, n, v, w