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:       Now let's begin the class . Who is on duty today ?  
 Person2:I am , sir .  
 Person1:        Please come to the front to have five minutes ’ free talk in English . Very well ! Whose turn is it to have a free talk ?  
 Person2:It's me , sir . But I am sorry I have forgotten to prepare for it .  
 Person1:        Well . Don't forget to perform your duty next time , ok ? Now , let's start our lesson . 

formal