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: ['d', 'p', 'k', '9679', 'x', 'j', '7481', '1815', 't', 'w', '6513', 'j', '5079', '5219', 'p', '9545', 'a', '1931', '9973', '8125', '5169', '2791', 't', 'd', '2057', 'e', 'x', 'y', '7409', 'u']

SOLUTION: a, d, e, j, k, p, t, u, w, x, y

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: ['q', '6283', '2953', 'd', 't', '3349', '2949', 'v', '6591', '8605', '1381', '7099', 'u', 'a', '5293', 'f', '3677', 'h', 'n', 'l', 'k', '8623', 'h', 'm', 'n', 'q', 'e', '8153', '1231', 'v', '6989', 'q', 'q', 'a', '5663', 'b', '5191', 'b', '8297', '6365', '5311', 'q', 'k', 'h']

SOLUTION:
a, b, d, e, f, h, k, l, m, n, q, t, u, v