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'll it be today , sir ?  
 Person2:Fill it up . Super Unleaded .  
 Person1:        Shall we check your oil and tires ?  
 Person2:I just checked the oil myself , but you can check the tires .  
 Person1:        ( The attendants fill the tank , clean the windscreen , and add some air to the tires . ) All right , sir , that'll be $ 26.50 .  
 Person2:I'll charge it . Here's my card . 

formal