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:       Good afternoon , everyone . The experiment is to start at 3 . Have you gone through the instructions ?  
 Person2:Yes , sir .  
 Person1:        Ok , now some points for attention . First of all , pay attention to safety ... Now , sign your names on the lab record , and after that you can start . If there is any question , just let me know .  
 Person2:Excuse me , sir . This air compressor doesn't work .  
 Person1:        Have you turned it on ?  
 Person2:Yes , I have .  
 Person1:        Ok , I will get you another one .  
 Person2:Thank you . 

formal