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 see who the suspect was ?  
 Person2:I got a perfect look at the suspect .  
 Person1:        Would you be able to pick him out of a line-up ?  
 Person2:That'll be easy .  
 Person1:        Please take a careful look at these five men .  
 Person2:Okay .  
 Person1:        Is the suspect in this line ?  
 Person2:I see him .  
 Person1:        Which number is he ?  
 Person2:The suspect is number four .  
 Person1:        Your cooperation is very much appreciated .  
 Person2:I'm happy to be of assistance . 

informal