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 would like to return this pair of shoes .  
 Person2:Do you have a sales slip ?  
 Person1:        Here it is .  
 Person2:Sorry , things on sale are not allowed to be refunded or exchanged .  
 Person1:        Oh , but this pair of shoes are a bit too tight . Could I change them for something bigger ?  
 Person2:All right . Wait a minute . 

informal