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: ['7227', '5231', 'l', '9243', '6777', '1235', '3585', 'v', '421', '1725', 'b', 'r', '6039', '9261', '6013', 'm', 'k', '791', 'q', '269', 'e', 't', 'a']
Output:
a, b, e, k, l, m, q, r, t, v