Given the task definition and input, reply with output. In this task, you are given a paragraph, event and an entity. The event is part of the given paragraph and it changes the state of the entity. Your task is to classify the state of the entity into three classes: 1) not exist, 2) unknown location and 3) known location. "not exist" means the entity doesn't exist in that state anymore. "unknown location" means the entity exists in that state but location is unknown. "known location" means the entity exists and location is known. 

 "process paragraph : : Fuel is converted to energy when air and petrol mix. The car engine burns the mix of air and petrol. Hot gas from the burning pushes the pistons. The resulting energy powers the crankshaft. Crankshaft powers the gears. The gears make the wheels roll. ", "event : The car engine burns the mix of air and petrol.", "entity : air" 

 not exist 