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: ['179', 'c', 'h', 'c', '473', '355', '313', 'f', 't', '41', 'u']
Student:
1, 3, 4, 5, 7, 9