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:       Thanks for the pizza . It was delicious .  
 Person2:It's okay .  
 Person1:        Next time , it's on me .  
 Person2:Don't be silly .  
 Person1:        I'm serious .  
 Person2:Alright . Next time , we can try some other flavors .  
 Person1:        Certainly . The vegetarian pizza looks pretty good . It must be very delicious .  
 Person2:Definitely . I really like Italian food . 

informal