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:       Are you free tonight ?  
 Person2:Yes , I am . What's wrong ?  
 Person1:        Would you please go to a dancing party with me ?  
 Person2:OK . No problem .  
 Person1:        As a matter of fact , I haven't danced for a long time .  
 Person2:But it's said that you dance wonderfully well .  
 Person1:        Thanks for flattering me . I think you dance a lot , right ?  
 Person2:No . Just occasionally .  
 Person1:        What are your favourite dances ?  
 Person2:I love rumba and waltz .  
 Person1:        How about samba ?  
 Person2:To tell the truth , I don't like it . It's too fast .  
 Person1:        Then I'll see you at six . Is that all right ?  
 Person2:OK . See you then .  
 Person1:        See you then . 

informal