Definition: You are given a conversation between two people. 'Person1:' and 'Person2:' are used to separate their respective dialogues. If the conversation begins with a question, label it '1' otherwise '0'.
Input:  Person1:     I've heard of ground-level ozone but can you explain what it is exactly ?  
 Person2:  Yes , it's one of the main air pollutants . Factories don't emit it directly into the air . It's actually formed when nitrogen oxides and VOC emissions come into contact with heat and sunlight .  
 Person1:      Sorry ? What does VOC stand for ?  
 Person2:  Oh , Vous are ' volatile organic compounds ' . That's a technical term for solvents or other chemicals found in things like paint .  
 Person1:      So , what damage does ozone do to the environment ?  
 Person2:  Well , it can cause smog , which can affect people's health - especially people with breathing difficulties . 

1