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 , sir . Is there anything I can do for you ?  
 Person2:Yes . I'd like to change some money , please .  
 Person1:        All right . How much would you like to change ?  
 Person2:Let me see . I think maybe 600 USD at least .  
 Person1:        Pardon ?  
 Person2:Six hundred US dollars .  
 Person1:        I'm sorry , sir , after 7  
 Person2:But I am badly in need of the amount . Might I ask you to make an exception for me ?  
 Person1:        I'm afraid we cannot help you , sir , because that would be violating the regulations . I owe an apology for doing nothing about it .  
 Person2:It's just too bad . I have to leave it as it is , and thank you just the same . 

informal