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:       Can I help you ?  
 Person2:Yes , I'd like to change some money to cover my expenses here . What's today's rate of US dollar against the RIB yuan ?  
 Person1:        Let me see , the buying rate is RIB 808 per $ 100 . How much would you like to change ?  
 Person2:$ 200 altogether .  
 Person1:        Would you mind showing me your passport ?  
 Person2:Here it is . And how much RIB shall I get ?  
 Person1:        Let me see . $ 200 makes RIB 1,616 . Here is the cash and exchange memo . Please check it .  
 Person2:That's correct . Thank you very much . 

informal