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:       Guess what ! I know something you don't know !  
 Person2:What's that ?  
 Person1:        How many planets are there in the solar system ?  
 Person2:That's easy . Everyone knows that there are nine .  
 Person1:        Not anymore ! Can you believe it ? They've decided that Pluto is not a planet anymore !  
 Person2:Nice try . I wasn't born yesterday , you know .  
 Person1:        I'm dead serious . They've decided that it's too small to be a planet , but actually they haven't yet agreed on how big something has to be in order to be a planet anymore .  
 Person2:That sounds crazy . But they can't just change their mind about things like that .  
 Person1:        Yes , they can . If you remember correctly , people used to believe that the world was flat .  
 Person2:I suppose you're right . They also used to think that they were so important that the sun revolved around them , not the other way around .  
 Person1:        We actually know relatively little about space and the cosmos .  
 Person2:Do you think that we'll one day be able to travel to another planet for a vacation ?  
 Person1:        I suppose we could actually live on a planet outside of the milky way .  
 Person2:Do you think we'll ever get to meet an alien from outer space ?  
 Person1:        I hope not . I think they would be a threat to those of us that lived on the Earth .  
 Person2:You're so old-fashioned . That's what people used to think about people from another country !  
 Person1:        Point taken . Hopefully one day , we'll live in an interplanetary society . 

informal