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', '8115', 'f', '5333', 'f', '3437', 'b', 'e', '5719', 'm', 'w', '95', '4863', 'k', '4895', 'a', '8179', 'm', '7919', '1731', '229', 'r', '1847', '7559', '6669']

SOLUTION: a, b, e, f, k, m, r, w, y

PROBLEM: ['r', 'j', '437', 'b', '5223', 'n', 'v', '437', 'd', '8285', 'k', 'j', 'r', 'p', 'n', 'e', 'n', 'j', 'o', '2651', 'j', '6365', 'q', 'q', '2159', 'g', '3641', '7727', 'c', '1197', 's', 't', 'n']

SOLUTION: b, c, d, e, g, j, k, n, o, p, q, r, s, t, v

PROBLEM: ['4911', '6023', 'i', '2035', 'y', 'a', 'q', '9287', '5233', 'r', '1169', 'r', '4241', '9423', '4201', '1507', 'z', '5607', 't', 'p', 'a', '4613', 'i', '9755', 'j', 'f']

SOLUTION:
a, f, i, j, p, q, r, t, y, z