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:       What's that book you have under your arm ?  
 Person2:It's the best seller everyone's been talking about for the last six months .  
 Person1:        How in the world did you get a copy ? I've put a hold on it at the public library for weeks and I'm still waiting my turn .  
 Person2:I checked it out of the rental library . It only costs five cents a day .  
 Person1:        Is it really worth paying for ?  
 Person2:I can't tell yet . I haven't got beyond the first chapter .  
 Person1:        If it's any good , I'll buy a copy when it comes out in the pocket edition . 

informal