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: ['3995', 'n', 'z', '8389', '7857', '3005', 'i', 'e', '1117', 'z', '8251', 'r', 't']

SOLUTION: e, i, n, r, t, z

PROBLEM: ['z', 'm', 'n', 'u', '9159', '7931', '5401', '1383', '8195', 't', 'x', 'q', 'r', '2535', 's', 'j', 'c', '8123', '2429', '5581', 'k', 'c', 't', 'i', 'm', 'o', 't', 'q', '4819', 't', '1649', 'r', 'y', 'z', '8813', '7451', '199', 'o', 'x', 's', 's', '6747']

SOLUTION: c, i, j, k, m, n, o, q, r, s, t, u, x, y, z

PROBLEM: ['e', 'u', 'b', 'o', 'b', 'e', '6295', '5153', 'n', '8263', '9499', 'i']

SOLUTION:
b, e, i, n, o, u