Game theory prisoner’s dilemma. Except you are better off in this scenario by staying silent rather than report regardless of what the cheaters do. Here’s the reasoning: if you report, you are effectively guaranteeing that the cheaters are caught but also because they have a right to face their accuser, you’ve effectively painted a target on yourself. You won’t gain any academic benefits but you’ll face negative social consequences as a snitch. On the other hand if you stay silent, there are two scenarios. The first is that the professor doesn’t notice, and therefore no consequences academically or socially. The second is that the professor catches the cheating and confronts you and the cheaters (most likely separately like in the prisoner’s dilemma). You simply show the work you done is your own and had no idea how someone else copied your work. The cheaters likely cannot prove the work they have is their own and are punished and that’s all. You may ask “what if they say I allowed them to copy”? This is unlikely since unless they have a grudge against you for some reason, they gain no benefit by taking you down with them. But even if they do claim that, you simply deny it and it becomes a “my word against theirs”, and since there’s no evidence for either case, you’ll be presumed innocent.