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: ['i', 'i', 'h', 'g', '5123', 'i', 'r', '3183', 'w', 'g', 's', '9777', '455', 'l', 'r', 'h', 'e', 's', 'v', '6823', '463', '9603', 'e', '947', '7071', 'c', '3373', 'j', 'w', 'm', 's', 's', '3483', '9567']

SOLUTION: c, e, g, h, i, j, l, m, r, s, v, w

PROBLEM: ['477', '3931', 'g', '5967', 'm', '9845', '1607', 'a', '1749', 'k', 'j', '7945', '9125', 'v', 'n', 's', '5185', '1117', '17', 'x', '4149']

SOLUTION: a, g, j, k, m, n, s, v, x

PROBLEM: ['3149', '1489', '687', 'n', 's', '6887', '2807', '4807', '4711', '3339', 'v', '6971', 'v', 'm', 'v', 'r', 'n', 'u', '2857', '3111', 'r', '5669', 'g', '6487', 'h', 'w', 'g', 'p', '6281', '1173', 'x', 'h', '4919', '5783', 'u', '2491', 'b', 'z']

SOLUTION:
b, g, h, m, n, p, r, s, u, v, w, x, z