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: ['9483', '501', 'j', 'k', '3103']

SOLUTION: j, k

PROBLEM: ['6769', '1057', '1021', 'n', '8231', '9173', '8123', 'a', '6053', 'q', 'y', '883', 'r', '1215', 'x', 'o', '9531']

SOLUTION: a, n, o, q, r, x, y

PROBLEM: ['k', '497', 'f', 'i', 's', 'y', 'f', 'l', '9533', '7213', '9371', 'f', '9859', '2331', 'd', 'q', 'l', 't', '5193', 'b', '1059', 'y']

SOLUTION:
b, d, f, i, k, l, q, s, t, y