Detailed Instructions: 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.
Q: ['371', 'y', 'p', 'd', 'k', '169', '79', 't']
A:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
1, 3, 6, 7, 9