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: ['9117', '1153', 'f', 'b', '9979']

SOLUTION: b, f

PROBLEM: ['7367', '9757', '9431', 'h', 'a', 'k', '5833', '6237', 'g', '3585', '8665', 'g', '7517', '1561', 'p', 'p', '1307', '3325', 'q']

SOLUTION: a, g, h, k, p, q

PROBLEM: ['q', '5545', '5947', '6187', '5731', '9271', '3265', 'g', 'm', '7691', '8043', '7191', '7969', 'h', '7995', 'e', 'i', '5309', '9063', 'c', 'o']

SOLUTION:
c, e, g, h, i, m, o, q