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 .  
 Person2:thank you for the dance .  
 Person1:        my pleasure . Let's go and have a drink .  
 Person2:ok . 

informal