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: ['p', '6123', '6961', 't', 'p', 'h', '9035', 'r', '6341', 'x', '3635', '5885', 't', '3543', '9567', '1787', 'o', '2991', 'k', '3441', '4091', 'a', 'r', '423', '9383', '7147', 'h', '663', 'd']

SOLUTION: a, d, h, k, o, p, r, t, x

PROBLEM: ['o', 'm', '8015', '787', '4787', '1727', 'f', 'e', 'c']

SOLUTION: c, e, f, m, o

PROBLEM: ['y', '3463', 'x', '4299', 'g', '9887', '8153', 'y', 't', '1763', '5543', '7931', '4155', '1319', '1513', 'v', 'h', 'g', '2955', 'h', '8919', '2857', '6057', 'i', '9081', '6555', 'o', 'a', 'p', 'x']

SOLUTION:
a, g, h, i, o, p, t, v, x, y