TASK 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.
PROBLEM: ['l', 'i']

SOLUTION: i, l

PROBLEM: ['o', '1099', 'r', '8995', 'o', '2909']

SOLUTION: o, r

PROBLEM: ['4811', '7531', 'k', 'x']

SOLUTION:
k, x