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: Consider Input: ['749', 'r', 'a', 's', 't', '5905', 'm', 'd', '8437', '4583']

Output: a, d, m, r, s, t


Input: Consider Input: ['q', 'g', 's', 'g', 'z', '987', '777']

Output: g, q, s, z


Input: Consider Input: ['3129', 'u', '4075', '1915', '3093', '4543', '4579', '8945']


Output: u