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:       do you remember where you were for the terrorist attacks on 9-11 ?  
 Person2:yes , I was in my apartment in Beijing . Where were you ?  
 Person1:        I was at home with my parents in New York City .  
 Person2:really ? Did you see the hijacked planes crash into and destroy the twin towers ?  
 Person1:        I didn't see the crash itself , but I did see the smoke and everything afterwards from my parents ' apartment building .  
 Person2:that must have been horrible . Did you go out at all that day to see what was going on ?  
 Person1:        no , we decided to stay in our apartment . With all the buses out of service and the underground trains at a halt , many people had no choice but to walk home . It was utter chaos .  
 Person2:did you know anyone who worked in the World Trade Center ?  
 Person1:        yes , my uncle's firm had an office in one of the towers .  
 Person2:did he survive ?  
 Person1:        unfortunately , he wasn't able to evacuate in time . He ended up dying in the tower .  
 Person2:I'm sorry . That must have really been a nightmarish day for you and your family .  
 Person1:        it was . The hijackers didn't have any respect for human life not even their own .  
 Person2:terrorist acts are deliberate and deadly and can affect every walk of life . 

informal