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:       What's that ?  
 Person2:It's a surprise !  
 Person1:        For me ?  
 Person2:Yes . Let's go inside and you can open it up .  
 Person1:        Wow ! It's big ! What could it be ?  
 Person2:I'll give you two clues . First , it cost more than $ 250 . And second , it's not big , but fat .  
 Person1:        What does that mean , not big but fat ? You didn't buy ... 

informal