A mathematician, a physicist and an engineer shared a hotel room Midnight, the waste basket caught on fire. The mathematician woke up first, looked at the fire and the water bottle next to it. He then wrote on a piece of paper ""between the fire and the bottle, a solution exists"", signed, and went back to sleep. The physicist wake up second, saw the fire and the mathematician's paper, then went to the basket and measure the paper in the basket and the water in the bottle, then went back and wrote ""half the bottle is sufficient"", signed, and went back to sleep. The engineer woke up last, saw the fire and the paper, processed to dump the whole bottle into the fire, and went back to sleep without signing anything.