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 think I'll write a book .  
 Person2:What about ?  
 Person1:        All of the time tested healthy habits from around the world .  
 Person2:You have done a lot of traveling . I'll bet you've learned quite a bit .  
 Person1:        The interesting thing is to see what really works and what's just hype .  
 Person2:Because you can see the results with the general public ?  
 Person1:        That's right . I think we all have much we can learn from each other .  
 Person2:I would buy that kind of book ! 

informal