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:       Well , it ’ s really too late . I have to go now .  
 Person2:Could you stay a little longer ?  
 Person1:        Sorry , I can ’ t.My mother doesn ’ t want me to be late . I really have to go .  
 Person2:In that case , I won ’ t keep you.Remember to give me a call .  
 Person1:        Thank you for your delicious meal . 

informal