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: ['7417', '2597', '2633', '7721', 'v', 'l', 'p', '4389', 'l', '3965', '6279', 'm', 'v', 'o', 'd', 'o', 'h', 'd', 'r', 'e', '8993', '2711', 'o', 'q', '1399', 'i']

SOLUTION: d, e, h, i, l, m, o, p, q, r, v

PROBLEM: ['749', 'r', 'a', 's', 't', '5905', 'm', 'd', '8437', '4583']

SOLUTION: a, d, m, r, s, t

PROBLEM: ['7343', '2599', 's', '9849', 'b', 'm', '3387', '5331', 's', '6405', 'h', '1051', 'r', '7219', 'z', 'w', '9713', '4909', '3723', '5051', '4959', '4149', '4527']

SOLUTION:
b, h, m, r, s, w, z