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: ['n', 'q', '6461', 's', '8565', '2237', '2071', '8143', '2977', '5511', 'j', 'o', '5793', 'j', 'm', 'n', '8031', 'j', '535', '5001', 's', 'y', '1737']

SOLUTION: j, m, n, o, q, s, y

PROBLEM: ['2819', 'k', 'u', 'a', '4575', 'a', 't', 'a', 'f', '1507', '415', 'w', 'o', 'o']

SOLUTION: a, f, k, o, t, u, w

PROBLEM: ['i', '9215', 'n', 'p', '4815', '8757', 'm', '1755', 'c', 'z']

SOLUTION:
c, i, m, n, p, z