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: ['y', 'b', 'r', 'f', '3745', 'n', '2921', '8133', 'r']

SOLUTION: b, f, n, r, y

PROBLEM: ['r', 'q', '3649', 't', '3941', 'z', '3729', 's', 'g', '6905', 'h', 'v', '1085', '6353', 'a', '9395', '5433', 'a', '2565', 'p', 'a', 'h', '1491', 'j', 'b', 'v', 'e']

SOLUTION: a, b, e, g, h, j, p, q, r, s, t, v, z

PROBLEM: ['8221', '5379', '4791', 'j', 's', 'o', 't', 'r', '2213', 'm', '3715', '1181', '435', 'g', 'g', '9553', 'n', 'c', 'u', 'r', '1497', '1817', 'g', 'j', '3605', 'k', '1857', '1619', 'g', '4829', 'b', 'o', 'p', '5737', '5693', '6539', '7639', 'd', 'j', '4989', '2201', '2497', 'j', 't']

SOLUTION:
b, c, d, g, j, k, m, n, o, p, r, s, t, u