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:       Oh my god ! It's 10:00 pm . I have to go . 
 Person2:Can ’ t you stay a little longer ? 
 Person1:        I am afraid not . 
 Person2:Say hi to your parents for me . I hope to see them soon . 
 Person1:        Thank you . Well , if you ever pass my home , please drop in . 
 Person2:Yes , I will . Take care , then . 
 Person1:        Yes , sure . Have a sweet dream ! 

informal