TASK DEFINITION: In this task, you are given an input list A. You need to extract and sort the unique digits used in the list in ascending order. Return -1 if there is no digit in the list.
PROBLEM: ['v', 'w', 'k']

SOLUTION: -1

PROBLEM: ['h', '477', 'w', '315', 'k', 'd', '367', '411', '207', 'b', '81', 'k', 'f', '107', '103']

SOLUTION: 0, 1, 2, 3, 4, 5, 6, 7, 8

PROBLEM: ['m', '297', '407', '309', 'p', 'r']

SOLUTION:
0, 2, 3, 4, 7, 9