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:       I'd better be going .  
 Person2:So soon ? Why don't you stay a little longer ?  
 Person1:        I wish I could , but it's already late .  
 Person2:Oh , it's a pity that you have to leave .  
 Person1:        Thank you for a wonderful meal .  
 Person2:I'm glad you enjoyed it . 

informal