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:       Oh , God . It ’ s late . I ’ m afraid I have to leave .  
 Person2:But you just got here . Can ’ t you stay a little longer and have some tea ?  
 Person1:        That ’ s very kind of you . But if I don ’ t go now I ’ ll miss the last bus .  
 Person2:That ’ s too bad .  
 Person1:        Thank you for your hospitality .  
 Person2:Thanks for coming .  
 Person1:        How about next time we meet at my place ? And I ’ ll treat you to Chinese food . I know how much you like it . We can order in and watch video too . Anything you like , I promise .  
 Person2:Great idea . I ’ m looking forward to it . See you then .  
 Person1:        Well . I really do have to go .  
 Person2:Good night then .  
 Person1:        See you tomorrow . 

informal