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: ['k', 'z', '303', 'a', 'f', 'q', 'i', '1475', '3453', 'd', 'w', '4037', 'z', 'h', 'k', '3547', '1561']

SOLUTION: a, d, f, h, i, k, q, w, z

PROBLEM: ['o', '9599']

SOLUTION: o

PROBLEM: ['u', 'm', 'r', '2437', '8315', '3603', '5001', 'd', '2093', 'y', 'b', '8489', '5595', '9819', 'e', '9053', '3243', '4257', '6557', '1651', '5595']

SOLUTION:
b, d, e, m, r, u, y