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:       Where were you last night , at exactly nine twenty PM ?  
 Person2:nine twenty pm , I couldn't say . I cann't remember .  
 Person1:        Are you sure you cann't remember ?  
 Person2:I've absolutely certain .  
 Person1:        Were you in or out ? Can you remember that ?  
 Person2:I'm not quite positive . I think I went out at about half pass nine .  
 Person1:        Did you see anyone come into the block flats ?  
 Person2:No , I didn't .  
 Person1:        Sure ?  
 Person2:Quite sure . 

formal