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: ['7641', 'e', 'c', 'p', '9917', 'u', '7335', 's', 'b', 'l', '2437', '759', 'h', 's']
Output:
b, c, e, h, l, p, s, u