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:       Excuse me , do you have A tale of Two Cities ? I'd like a copy of it .  
 Person2:Who is the author ?  
 Person1:        Charles Dickens .  
 Person2:Sorry , we ' re sold out right now.Please come back next week .  
 Person1:        Ok , Thanks . 

informal