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I was able to get N=2000 here (C++), so you don't need to have any constrains ;) This kata is mostly about how much performance you can squeeze before reaching a timeout.

Description in other languages has information about upper bound, but C++ misses this info.
If I see correctly, max n is 1000.

What are the constraints for N in C++ tests? Every other language has them listed (For example, Python says 1<=N<=1000), where C only says "All possible values are tested." I assume it is not testing every integer input, so what should this say?

^ x -1 is not accepted, because the correct answer is / 1 x. These are equivalent expressions, are they not? Language is python, test is basic ln(x).