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:       Who's that over here ?  
 Person2:That's the new teacher .  
 Person1:        What do you think of the teacher ?  
 Person2:She's very nice .  
 Person1:        What does she teach ?  
 Person2:English , of course .  
 Person1:        Is she your teacher ?  
 Person2:Yes.She teaches our class three times a week .  
 Person1:        Can she speak Chinese to her students ?  
 Person2:Not very much .  
 Person1:        It's a good thing you can speak English ! 

informal