Cocoa app, Xcode Console - Red Numbers

I'm trying to debug an application that compares up to 9 numbers in a certain way. It's working great for up to 4 or more numbers but once you try an run 3 or less it starts returning a NaN error where it should be returning a zero.

I'm working through the console and ~20% of the numbers are highlighted in red. Before I get to checking the code here I wanted to see what the red vs black numbers mean and if that applies to what I'm looking for. I don't think it applies because when the application is working correctly as I go through the debugger some of the numbers are still red. However I still would like to learn.

If it's something obvious I apologize because I'm both starting out and just letting Xcode do the memory management.

Thanks in advance!

Graham

** Edit

I'm not too worried about debugging right now, I want to give it an honest college try before I come back for help but the error is coming when I use a combination of 5000/3000/5500. It's not limited to that specific arrangement and I have it narrowed down to one of my functions.

As shown it is giving me the correct number in the +/- which is the end and I've run about 10 scenario's that are all correct as long as there is more than 4 stacks.

As asked it开发者_如何学JAVA is in the test phase and I should have mentioned that it was my variables that are colored.

That's not a console. That's the debugger. The red values are values that have changed. It lets you easily see how the values change over time by drawing your eyes to the interesting rows.