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: ['7203', '8715', '3193', 'w', '7159', '8535', 'i', '2425', 'j', 'f', '6709', 'w', 'w', 's', 'e', '9337', 'r', 'r', '5255', '1707', 'u', '1443', 'e', 'e', 'v']

SOLUTION: e, f, i, j, r, s, u, v, w

PROBLEM: ['4993', 'n', '7115', 'f', 'd', 'q', '249', '3203', 'w', '5689', '4103', '7129', '603', 'e', 'z', '5571', '3241', '6029', '2721', '8451', 'o', '7841', 'p', '6271', 'r', 'b', '9481', '4045', 'v']

SOLUTION: b, d, e, f, n, o, p, q, r, v, w, z

PROBLEM: ['s', 'w', 'h', 'n', '7743', '7451', '8805', '7553', 'i', 'i', 'h', 'w', '213', 'f', 'q', 'o', 'o', '4017', 'b', '2937', 'k', '6525', 'm', '6373']

SOLUTION:
b, f, h, i, k, m, n, o, q, s, w