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:       Hello , Jason . Are you free this Saturday evening ? 
 Person2:Yes . I have no plans . 
 Person1:        Would you like to Come to our barbecue ? 
 Person2:Yes , that sounds wonderful . 
 Person1:        OK . See you then . 
 Person2:But wait , wait , will there be food that is not meat ? You know . I'm a vegetarian 
 Person1:        Hey ! I didn't know that ! When did you become a vegetarian ? 
 Person2:The other day , I decided that I needed to loose more weight so I am going to try to be a vegetarian . And you know what ? I don't miss the taste of meat . 
 Person1:        Relly ? That's amazing . 
 Person2:Yes , it really is . After having vegetarian diet . I have much more energy , I need less sleep , I feel calmer . I can maintain an ideal body weight without worrying about how much I eat and I can think more clearly . 
 Person1:        Are you kidding ? I really don't think that you think less clearly on non-vegetarian diet . 
 Person2:Yes , maybe . But I feel better since becoming a vegetarian . Maybe you could also have a try . 
 Person1:        Maybe I'll also have a try some day , but I'm afraid that it would be difficult for me to refuse meat . 
 Person2:Maybe you would change your mind after having a vegetarian diet . 
 Person1:        We'll see . Anyway , I'll prepare some vegetarian food for the barbecue . See you then ! 

informal