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: ['l', '6313', '3199', 'w', '249', '8747', '7391', '3871', '173', 'x', 'o', '8647', '4413', '3645', '6123', '701', 'q', '2147', '4289', '7333', '533']

SOLUTION: l, o, q, w, x

PROBLEM: ['3035', 'f', 'k', 'e', '3023', 'p', '9667', '5277', '4757', '8433', 'g', '1399', '7721', 'n', 'p', '7469', '7581', '5679', 'g', 'q']

SOLUTION: e, f, g, k, n, p, q

PROBLEM: ['f', 'x', 't', 'm', 's', 'i', '5001', 'n', 'c', '303', '5947', '8843', '9087', 'y', '1787', '9019', 'y', '9369', '3389', '3545', 'x', '2987', 'n', 't', 'i', 'q', 'h', 'g', '7751', '5271', 'o', 'q', '7129', '243', 'r', '5165', '7883', 'g', '8367', 's', '4963']

SOLUTION:
c, f, g, h, i, m, n, o, q, r, s, t, x, y