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 . 

informal