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: ['1367', 'h', '4153', '1587', 'h', 'b', 'n', 'u', 'n']

SOLUTION: b, h, n, u

PROBLEM: ['8235', 't', '1695', '9899', '3633', 't', '1823', 'r', 'x']

SOLUTION: r, t, x

PROBLEM: ['895', '2049', '8839', '1773', 'v', '467']

SOLUTION:
v

