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: ['2469', '4757', '3251', 's', '3331', 'u', 'x', '1373', '4017', '1493', '1951', 'y', '5843', '6815', 'b', 'q', '6949', 'e', 'n', 'g', '9169', 'y', 'd', 'g', 'f', 'y', '4105', '3225', '9561', 'y', '1085', '9243']
Solution:
b, d, e, f, g, n, q, s, u, x, y