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'm not satisfied with it .  
 Person2:Why not ? What's wrong with it ?  
 Person1:        Sometimes it goes fast . And sometimes it goes slow . And the alarm doesn'twork , either .  
 Person2:Would you like another one ?  
 Person1:        No . Can I have my money back ?  
 Person2:Hmm ... have you got a receipt ?  
 Person1:        A receipt ?  
 Person2:Yes . I must see your receipt . You can't have your money back without receipt .  
 Person1:        Oh , I'm not certain , but I think I've lost it . 

informal