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: ['4299', 'b', '4171', '7639', '6609', '927', '5249', 'o', 'p', '9851', 'e', '1311', '3777', '7799', '7687', '8809', 'c', 'r', '47', '1925', '1847', 'r', 'd', 'r', '1871', '5935', 'r', '2283', 'p', 'p', '2727', 'c', 'i', '7357', 'y', '5103', '6115', 'q', 'w', 'u', '9201', '4221', '7717', 'o']

SOLUTION: b, c, d, e, i, o, p, q, r, u, w, y

PROBLEM: ['c', '8389', 'j', '6113', '5843', 'f']

SOLUTION: c, f, j

PROBLEM: ['8299', 'm', 'b', 'l', 'x', 'q', '591', '4155', '6005', 'a', 'c', 'y', 'c', '5193', '8547', 'r', '789', '2179', '923', '7451', '419', '4657', 'x', 'u', '635', 'u', '429', 'i', 'c', 'p', 'p', '6281', '6903', '8231', '7365', '6227', '5025']

SOLUTION:
a, b, c, i, l, m, p, q, r, u, x, y