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:       The band is pretty good . How do you like the music ?  
 Person2:It's very nice . I haven't heard live music in a while . This is fun .  
 Person1:        Well , then , may I invite you for the next dance ?  
 Person2:Of course . But I'm afraid I'm not much of a dancer ...  
 Person1:        Don't worry . I'm not much of a dancer myself .  
 Person2:You're dancing so well .  
 Person1:        You dance beautifully too .  
 Person2:When did you learn to dance ?  
 Person1:        In college . But I don't dance very often . What's your favourite dance ?  
 Person2:It's hard to say . It depends . But I love the waltz .  
 Person1:        How about tango ?  
 Person2:Oh , I like it . It's such a beautiful dance , but I can't do it well . What about you ?  
 Person1:        Tango is my favorite . Anything but hip-hop or the foxtrot . ( the music has stopped )  
 Person2:Thank you for the dance .  
 Person1:        My pleasure . Let's go and have a drink .  
 Person2:OK . 

informal