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:       Professor , I am going to need to leave class early today .  
 Person2:What is the problem ?  
 Person1:        I need to go to the airport to pick up a relative .  
 Person2:Are you planning on having someone take notes for you ?  
 Person1:        Yes , I've got that part covered .  
 Person2:When , exactly do you need to leave ?  
 Person1:        I don't need to leave until the very end of class .  
 Person2:Fine , but next time try and not have to miss class again .  
 Person1:        Thanks , Professor . See you later !  
 Person2:See you later ! Drive carefully . 

informal