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: ['7677', '4069', 'b', 'w', '4381', 'b', '5757', '711', '765', '8347', '6547', '9527', '945', '5333']

SOLUTION: b, w

PROBLEM: ['6175', '9441', '7127', '5979', 's', '1367', 'e', 'm', '7083', '1787', '8375', '2851', '3475', 'r', '697', 'g', 'z', 'm', '4207', 'c', '7971', 'z', '9339', 'd', 's', '3507', '9003', 'i', 'y', 'w', 'j', 'i']

SOLUTION: c, d, e, g, i, j, m, r, s, w, y, z

PROBLEM: ['n', '2433', 'x', 'f', '6981', 'b', '1953', '7163', '7009', 'j', 'j', 'p', 'a', 'x', 'i', '5211', 'p', '9383', '6567', '5059', 'h', '7683', 'w', '823', 'e', 'm', '8761', 'b', 'e', '3249', 'x', '7041', 'h', 't', 'e']

SOLUTION:
a, b, e, f, h, i, j, m, n, p, t, w, x