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: ['315', '9975', '3013', 's', '6131', 'e', 'e', 'u', 'a', '1729', 'g', 't', 'y', 'f', '7523', 'e', 'g', '489', 'm', 'p', 'f', 'e', '2077', 'e', 'g', 'c', 'l', '6389', 'k', 'b']

SOLUTION: a, b, c, e, f, g, k, l, m, p, s, t, u, y

PROBLEM: ['4041', 'l', 'g', '9571', '9295', '1395', 'l', 'p', 'f', 'w', 'g', '1721', '2421', 'w', 'z', '2235', 'p', '7851']

SOLUTION: f, g, l, p, w, z

PROBLEM: ['2599', '5229', '6093', '3407', '5251', '4457', '6363', 'l', '8777', '3', 'k', '887', 'f', '1619', 'z', '2535', '625', '2753', '2353', '3639', '8859', 'k', '1247', 'j', 'n', 'e', 'n', '4659', '5091', 'r', 'j', 't', 'c', '3301', '4405', 'r', 'a', 'v', '1815', '2141', '8487', 'b', 'w', '5829']

SOLUTION:
a, b, c, e, f, j, k, l, n, r, t, v, w, z