Definition: You are given a conversation between two people. 'Person1:' and 'Person2:' are used to separate their respective dialogues. You are required to assign a label 'formal' if there is an absence of emotion and a presence of questions anywhere within the conversation. If such pattern is not found assign the label 'informal'.
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 . 

formal