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:       Did you watch TV last night , Rose ?  
 Person2:Yeah . I saw a science program . It was quite interesting .  
 Person1:        What was it about ?  
 Person2:Mars . Scientists say there might be water on it .  
 Person1:        If so , we may live there someday .  
 Person2:I hope so . Did you know the US successfully sent two robotic explorers to Mars last month ?  
 Person1:        Sure . I heard about this on the TV . On January 3rd , 2004 , Explorer Spirit landed near the so-called Guser Crater . And three weeks later , Spirit's twin explorer , Opportunity , landed on Meridian Planum named by scientists .  
 Person2:Yes . Both have sent back pictures of the planet . And the latter did a better job . 

informal