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:       May I help you ?  
 Person2:I would like to find this book .  
 Person1:        Is there a problem ?  
 Person2:I don ’ t think you guys have it .  
 Person1:        You should look it up on our computer .  
 Person2:I did that .  
 Person1:        What came up ?  
 Person2:It should be on the shelf , but I didn ’ t see it .  
 Person1:        I can try to get the book from a different library .  
 Person2:I didn ’ t know you could do that .  
 Person1:        I will call you when I find it .  
 Person2:I appreciate your help . 

informal