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', '6615', 'r', 'q', '3803', '4641', '9775', '7719', 'n', '6571', '2723', '6919', 'e', 'f', '1919', '6963', '2581', 'y', '713', 'w', 'w', 'w', 'l', 's', '3993', '9563', '9365', '9277', '103', '2737', 'y', '6005', '9763', 'p', '261']

SOLUTION: e, f, l, n, p, q, r, s, w, y

PROBLEM: ['3223', 'h', 'w', 'f', 'y', '1667', '8843', '8759', '9203', '3305', '3549', '5507', '6251', 't', '8319', '9121', '6643', 'u', '4273', '4429', '7543', '7909', '789', '9183', '5729', 'd', '7063', 'b', '6677', 'w', 'x', 'x', 'z', '769', 'p', 'd', 'h']

SOLUTION: b, d, f, h, p, t, u, w, x, y, z

PROBLEM: ['k', 'q', 'y', 'c', 'w', 't', '2637', '5069', '7789', 'u', 'c', 'n', '4349', 'c', 'o', '7397', '1837', 'r', '449', '7955', '8871', 'e', '427', 'b', '5249', '3055', 'i', 'v', 'v', '3861', '2143', '2623', '9591', '4367', 'i', '7545', 'd', 'a', '2595', '6895']

SOLUTION:
a, b, c, d, e, i, k, n, o, q, r, t, u, v, w, y