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: ['5345', 'f', '6605', 's', 'q', 'w', 'p', 'o', 's', 'u', 'i', '7339', '8379', 'h', '9547', 'b']

SOLUTION: b, f, h, i, o, p, q, s, u, w

PROBLEM: ['8859', '575', 'l', 'e', '6575', '1303', '8643', '1395', '3171']

SOLUTION: e, l

PROBLEM: ['b', 'j', '9039', 'r', 'm', '6187', 'k', 'z', 'g', 'c', 't', '4933', 'f', 'g', 'l', '6297', '201', 's', '5771', 'l', '5829', '4437', 'f', '5095', '9043', 'w', '3237', '3185', '6687', 'm']

SOLUTION:
b, c, f, g, j, k, l, m, r, s, t, w, z