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: ['7417', '2597', '2633', '7721', 'v', 'l', 'p', '4389', 'l', '3965', '6279', 'm', 'v', 'o', 'd', 'o', 'h', 'd', 'r', 'e', '8993', '2711', 'o', 'q', '1399', 'i']

SOLUTION: d, e, h, i, l, m, o, p, q, r, v

PROBLEM: ['7799', '8163', '3389', 'x', 'k', 'm', '6085', 'f', '1131']

SOLUTION: f, k, m, x

PROBLEM: ['g', '9421', '4097', '9355', 'u', 'i', 'o', '419', '9075', '3215', 'v', 'l', '9027', '3563', 'h', 'i', '6339', 'c', 'q', '9097', 'q', 'k', 'v', '4181', '1395', '1363', '243', '5581', '3041', '7255', 'k', 'p', '9657', 'f', '6329', '7989', '255', '3503', 's', 'd', '3395', 'w', 'u', 'n']

SOLUTION:
c, d, f, g, h, i, k, l, n, o, p, q, s, u, v, w