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:       We ’ re going to the movies . Will you join us ?  
 Person2:I ’ m very sorry I can ’ t .  
 Person1:        Why not ?  
 Person2:I ’ m afraid I have some business to attend to .  
 Person1:        Then would you like to have lunch with us ?  
 Person2:I ’ d love to but I have to help John with his math problems right now .  
 Person1:        Would you like me to give you a lift ?  
 Person2:No , thanks . His home is not far and I can walk there .  
 Person1:        Come on . It ’ s no trouble at all .  
 Person2:Ok , thank you . 

informal