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:       Can I help you ?  
 Person2:Yes , I ’ m doing some research on Roman civilization . Do you have any books on the subject ?  
 Person1:        These books over here are about ancient history . They might be helpful .  
 Person2:Can I check this one out ?  
 Person1:        I ’ m sorry . It ’ s for reference only , so it must stay in the library . But you ’ re welcome to look through it .  
 Person2:Ok . And I ’ d like to check these books out .  
 Person1:        All right . They ’ re due back next Wednesday .  
 Person2:Thanks for your help . 

informal