Detailed Instructions: 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.
See one example below:
Problem: ['8129', 'a', '4245', 'y', 'm', 'a']
Solution: a, m, y
Explanation: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.

Problem: ['7981', 'p', 'h', 'e', 'b', '6957', '241', '3851', 'y', '3687', 'n', 'l', 'q', 'o', 'z', '3533', '7399', '3029', 'k', '7407', 'w', 'd', '5237', '5759', '8213', '5425']
Solution:
b, d, e, h, k, l, n, o, p, q, w, y, z