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:       Professor , I've handed in my paper . Did you read it ? 
 Person2:Yes . You've done a good job . But there's one thing . You should narrow down your topic . 
 Person1:        What about water pollution instead of pollution ? 
 Person2:Well done ! 

informal