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: ['9579', 'm', 'v', 'r']

SOLUTION: m, r, v

PROBLEM: ['1595', '2915', 'o', 't', 'c', 'h', '3969', '5407']

SOLUTION: c, h, o, t

PROBLEM: ['1435', 's', 'y', '2497', 'g', '1343', 'o', '3893', '3791', 'd', 'w', '6151', 'q']

SOLUTION:
d, g, o, q, s, w, y