 In this context, we will however focus on planning and tree search. So what is planning? If we think about planning at a high level, it's just we want to choose potential future that we prefer. Of course, the world only allows us to choose certain futures, other futures, and possible. And we saw a simple version of planning in the value snap judgment, where I plan just one step into the future. Of course, we could iterate that to go further and further in the future. Now, we might not want to do this already, because there are lots of futures that are just really bad. For example, I could fall down, break my leg right now. It's not very useful for me giving the lectures. So in lots of ways, avoiding us to spend compute or thoughts about futures that we don't want to enter anyways is not very helpful for us. So let's see how a tree that describes potential futures would actually look like. And for you, estimate how many such trees exist.