3. Around a campfire, eight natives from four tribes are sitting in a circle. Each one says to the person on their left: “if we don’t count us, there is no one else from my tribe here.” It is known that the natives lie to strangers and tell the truth to their own. How many natives can there be from each tribe?
Solution. There must be at least two natives from one tribe; a unique native could not lie to a neighbor that there is no one else from their tribe. Since there are only four tribes, there are two from each tribe.