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: ['c', 'h', '8655', 'r', '7531', 's', 'r', 'w', 'e', 's', 'p', '1709', '5447', 'b', '5855', 'w', 'f', 'i', '7809', 'q', '1975', 'z', '4037', 'k', 'l', 'z', 'g', '9739', '8801', '3405', '6549', '4561', 'd', '1669']

SOLUTION: b, c, d, e, f, g, h, i, k, l, p, q, r, s, w, z

PROBLEM: ['d', 'a', '6931', 'c', 'u', 'z', '9713', 'v', 'm', 'e', 'k', 'o', '9705', 'a', '5373', 'c', '2983', '8097', 'h', '3039', 'g', 'f', 'n', 'v', '853', '8227', '7573', 'j', 'h', 'k', 'o', 'k', '8897', 'd', 'g', 'd', 'd', '4039']

SOLUTION: a, c, d, e, f, g, h, j, k, m, n, o, u, v, z

PROBLEM: ['n', 'x', '853', 'k', '5557', '9087', 'r', 'j', '4677', '2393', '1111', 'z', 'u', '5375', 'z']

SOLUTION:
j, k, n, r, u, x, z