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:       How do you like waltz ?  
 Person2:It's very nice , I like it very much .  
 Person1:        May I invite you for the first dance ?  
 Person2:My pleasure . But I'm afraid I'm not much of a dancer .  
 Person1:        In fact , I took up dancing quite recently , too .  
 Person2:Oh , really ? But you're doing the tango wonderfully well .  
 Person1:        I'm glad you say so , you dance beautifully too . It's lucky that I got a partner .  
 Person2:Thank you for your compliments . It's just that you are a good leader . Do you like the samba and waltz ?  
 Person1:        Yes . And what dances do you like best ?  
 Person2:Waltz is my favorite . I like it better than any other dances .  
 Person1:        Oh , the music has stopped . Thank you for the dance .  
 Person2:My pleasure . Let's go and have a drink .  
 Person1:        Fine . 

informal