Definition: 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.
Input: ['w', '9697', '7911', '3979', '3569', '2709', '8979', '7933', '7389', 'z', 'b', '9603', 'f', '5149', 'p', 'd', '5897', '2067', '5819', 'i', '3107', '9427', '2047', 'w', '881', '9091', '9933']
Output:
b, d, f, i, p, w, z