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: ['v', '6635', '5395', '3263', '4391', 'h', '1521', 'f', '9861', '6125', '1673', '3679', '8681', '4967', 'f', 'a', 'c', 'k', 'n', '4155', 'e', 'm', 'i', '1699', 'r', 'f', 'u', 'r', '3451', 'v', '7239', 'o', '4359', 'l', 'a', '2925']

SOLUTION: a, c, e, f, h, i, k, l, m, n, o, r, u, v

PROBLEM: ['6249', '1235']

SOLUTION: -1

PROBLEM: ['c', '9151', 'e', '8555', '7419', 'u', '2715', 'b', 'y', 'e', '2093']

SOLUTION:
b, c, e, u, y