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: ['z', '8763', '6399', '45', '6731', 'v', '441', '4763', 'u', '8741', 'r', '9143', 'd', 'p', '2241', 'y', '6523', 'y', 'w', '6771', 't', 'r', '9239', '295', 'z', '461', 'b', '9217', '2597', '1249', 'r', 'i']

SOLUTION: b, d, i, p, r, t, u, v, w, y, z

PROBLEM: ['t', 'u', 'y', 'y', 'b', 'x', 'q', '3713', '2679']

SOLUTION: b, q, t, u, x, y

PROBLEM: ['641', '4093', 'u', 'i', '21', 'f', 'g', '1341', 'c', '8491', '313', '2885', '8445', 'l', 'p', 'm', 'y', '5311', '7825', 'o', 'd', 's', 'j', '4435', '3665', 'a', 'x', 'f', 's', '4349', 'c', 'p', 'e', '4725', 'j', 'h', 'h', '3507', 'f', 's', '7899', 's', 'd', 'q', '2605']

SOLUTION:
a, c, d, e, f, g, h, i, j, l, m, o, p, q, s, u, x, y