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:       So how long have you known Mary ?  
 Person2:Only four days .  
 Person1:        Only four days ! That's so short , and you seem so crazy about her .  
 Person2:I know . I can't help thinking about her . She's always on my mind . 

informal