All of them.

[No, he doesn't know what kind of task he's facing, but even if he did, it probably wouldn't make a difference.]

Okay, so, two plus two makes four, right? You can still subtract two from four to get two again. If two things get put together, there might still be a way to take them apart. I don't know what it is yet, that's why I want to talk to the dwarves. Even if they don't know how, maybe we can work together to make a new way. Either way, I've got to try.