I agree with having more hints, but we're taking this one step at a time.
"check the red folder" is guaranteed to happen, I was just hoping that we can make it so instead of "red" it's something more people can recognize.
It's possible there's no set of 16-20 colors that satisfies these constraints, I don't know, but I'd rather hear that answer from someone with firsthand experience before making a decision for them.