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: ['t', '6461', 'p', '3501', 'v', 's', 'r', '7521', 'q', '2829', '9137', '4403', 'j', 'd', '89', 'a', '6769', '4555', '6257', 'b', '5879', '2703', 'z', '7883', 'o', 't', 'i', '5493']
Output:
a, b, d, i, j, o, p, q, r, s, t, v, z