What would you do if you found €22 in a book in your local library?

We have a small library in our village and the books are not in very good condition. This is the only opportunity to borrow English books in my village. I borrow books from the library every week for 6-7 months. I never borrowed a children's book yet. Today, I borrowed a children's book and found €22 in it. <br><br>I don't know what to do because I have never found this amount of money in my life in any place. It is obviously a lot for a kid, and I think I can give it to the library as this book belongs to a kid, and I'm sure the kid will be sad.<br><br>What would you do if you were in my shoes?