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: ['6697', 'j', '1571', '4989', 'o', '1143', 'i', '2969', '2541', '4899', 'i', '4751', 'n', 'b', '801', '4357', '3855', '49', 'm', '211', '7281', '121', '5231', '8313', '8967', '8043', '7699', 'r', '4315', '8637', '3339', '4437']
Solution:
b, i, j, m, n, o, r