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:       Is this seat taken ?  
 Person2:No . Please sit down .  
 Person1:        Thanks .  
 Person2:Are you also going to Beijing ?  
 Person1:        Yes , on a business trip . How about Yuu ?  
 Person2:I'm taking a vacation to visit a friend there . Have you ever been there before ?  
 Person1:        Yes , I Went there once last summer .  
 Person2:Really ? What did you think ?  
 Person1:        I think it is amazing . You can enjoy both the traditional Chinese culture as well as the vitality of a modern cosmopolitan city . The only thing I didn't enjoy was the subway .  
 Person2:Was it that crowded ?  
 Person1:        Yes.These were always so many people.After taking the subway during the rush hour , you'll envy sardines in their cans .  
 Person2:Oh , maybe I can take the bus or even rent a car .  
 Person1:        That's a good idea . Wish you a great vacation !  
 Person2:Thank you very much ! 

informal