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:       What can I do for you today ? 
 Person2:I need to return a book . 
 Person1:        Can I do anything else for you ? 
 Person2:I would also like to check out this video . 
 Person1:        Is that all ? 
 Person2:Yes , just the video . 
 Person1:        May I see your library card ? 
 Person2:Here you go . 
 Person1:        You have to take care of this video . 
 Person2:Oh , I will . 
 Person1:        You will be fined if you damage it . 
 Person2:I understand . Thank you very much . 

formal