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:       It's very kind of you to come and see us off .  
 Person2:My pleasure.What a pity you have to leave so soon !  
 Person1:        We would stay longer . but I've got to attend a meeting tomorrow morning . Thank you for your warm hospitality .  
 Person2:You're welcome . Maybe next time we'll come to see you .  
 Person1:        My wife and I will look forward to it .  
 Person2:I promise the next holiday I have we're coming to visit . Oh , what's your flight number ?  
 Person1:        lt's Flight No . 302 , Northwest Orient Airlines .  
 Person2:They just announced the boarding call .  
 Person1:        Then we've got to get going .  
 Person2:OK . Bon voyage and a safe landing .  
 Person1:        Thank you again for all your help .  
 Person2:Bye . 

informal