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 like NBA very much .  
 Person2:Did you watch NBA games before you came to the U . S . ?  
 Person1:        No , I didn't .  
 Person2:What a pity !  
 Person1:        Do you like NBA ?  
 Person2:Yes , of course .  
 Person1:        Who do you like best of the NBA players ?  
 Person2:Kobe .  
 Person1:        So do I .  
 Person2:Let's go to watch an NBA game tonight , shall we ?  
 Person1:        That's fine . 

informal