aarrghh!! I was trying list.removeDuplicates() :}

i can see why i would like it, but definatly wouldnt expect it to behave that way

The arguments scope can actually be treated as either an array or a struct, though it is in fact neither. I am not sure of the best documentation page for this, but I did find the following:

https://helpx.adobe.com/coldfusion/developing-applications/building-blocks-of-coldfusion-applications/writing-and-calling-user-defined-functions/working-with-arguments-and-variables-in-functions.html

Why does this work, arguments is a struct?

Yes you're absolutely correct. The test cases apparantly didn't test for this. Made a new solution that works with 2 negatives.

Would this not fail if both n and m were negative, or am I missing something?