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:       The Blacks got divorced .  
 Person2:Really ? Why ?  
 Person1:        Mr . Black has been getting a little on the side .  
 Person2:Really ? I am surprised . He doesn't look like a guy who'd ever cheat on his wife , does he ?  
 Person1:        No , he doesn't . Anyway , his wife found out that he has been two-timing for a long time .  
 Person2:Well , I am really surprised . By the way , have you done anything behind my back ?  
 Person1:        No . The only thing I've ever done behind your back is zipping you up .  
 Person2:I like that joke , but I hope it's true . 

informal