 Okay, so, I don't know, what's the oxidation number of these atoms? Okay? These atoms in these compounds. Okay, so how would we figure this out? So, oxygen is always minus 2, right? There's 4, right? So that's minus 8 together. So, nitrogen plus 4, okay? So, nitrogen equals plus 4, oxygen equals minus 2. What about this one? Hydrogen's always plus 1. Hydrogen's always plus 1, and oxygen's always minus 2. Okay, so those are oxidation numbers. So, that was 4 problems in like 2 seconds, you know? So, any questions on that stuff?