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:       I am going to give you an end-of-the-unit test this Friday . Please be prepared for it .  
 Person2:Would you please tell us how to review our lessons ?  
 Person1:        Review all the lessons in this unit and see if you can understand the main idea of each lesson .  
 Person2:Any other requirements ?  
 Person1:        Phrases and sentence patterns are also very important . You should know how to use them .  
 Person2:Should we remember all the new words and expressions ?  
 Person1:        Certainly .  
 Person2:Sorry , I don't quite understand some difficult points in this unit . I wonder if you could help us to solve the problems .  
 Person1:        Well . When you review your lessons , mark the places which you don't understand , then I will give you some coaching .  
 Person2:When shall we have a coaching period ?  
 Person1:        How about tomorrow ?  
 Person2:Ok . 

formal