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:       Have you made a reservation ?  
 Person2:Yes , I have booked a table for four . My name is Liu Fan .  
 Person1:        We have had a window table reserved for you . This way , please .  
 Person2:Thanks .  
 Person1:        You're welcome .  
 Person2:Can we see the menu , please ?  
 Person1:        I'll bring it over .  
 Person2:Anything good for this evening ?  
 Person1:        We have squirrel shaped mandarin fish , seeds prawn , etc .  
 Person2:Very good , we'll take them all . 

informal