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 need some books on hardware .  
 Person2:There's many books here.What about these ?  
 Person1:        Great ! They're the very books I want.May I borrow two books ?  
 Person2:Sure.But you can only keep them for a week .  
 Person1:        I see.Thank you . 

informal