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 so earlier this morning , Mr . Li ! You just came back yesterday , you should have rest much more .  
 Person2:I'd like to have rest , but I have many things to do .  
 Person1:        How about this post-trip ?  
 Person2:It's very good , and the result isn't too bad .  
 Person1:        Really ?  
 Person2:Of course . I will write a report about this post-trip , and then you'd better type it at the moment , OK ?  
 Person1:        OK , it's no problem .  
 Person2:( Afternoon ) Miss Liu . Are you typing my report ?  
 Person1:        Yes , what can I do for you ?  
 Person2:Nothing . I just tell you take care of it when you type , especially the address and telephone number of those new guests . You should make sure that it's no mistaken .  
 Person1:        OK , please don't worry about it . You should set your mind at rest .  
 Person2:Ha , I know you are great secretary .  
 Person1:        Thanks your flatter . 

informal