Teacher: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.
Teacher: Now, understand the problem? Solve this instance: ['c', 'n', '375', 'r', '107', 'g', '243', 'c', '299', 'd', 'y']
Student:
0, 1, 2, 3, 4, 5, 7, 9