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:       Let's go to the cinema by bus .  
 Person2:Better take the subway . It's far quicker and more convenient .  
 Person1:        OK , it will be a new experience for me .  
 Person2:We have a rather comprehensive subway system here . You can get almost anywhere rather quickly on a subway , especially at this time of day when the traffic is heavy .  
 Person1:        Where do we pay the fare ?  
 Person2:Just give the man sitting there three yuan and he'll give you a ticket .  
 Person1:        Do I have to pay an additional fare to change trains ?  
 Person2:No , you don't have to . Here comes the train . Be careful ! Subway doors open and close automatically . 

formal