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: ['2435', '4021', 'l', '461', '1243', 'c', 's', 'i', 'l', '959', 'e', 'a', '9331', '1921', 'g', '1643', 'h', 'f', '2673', '3055', '7531', 'i', 'i', 'f', '3857', '9899', '9857', '9231']
Output:
a, c, e, f, g, h, i, l, s