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:       Hello . May I speak to Mary , please ? 
 Person2:Speaking . Who's calling , please ? 
 Person1:        Hi , Mary . This is Tom . 
 Person2:Oh , hi , Tom . How've you been ? 
 Person1:        Just fine . I say . Aren't you busy tomorrow evening ? 
 Person2:Let me see . Uh-huh ... no , I guess I'll be free . 
 Person1:        Well , uh ... why not dine out together and go to the movies ? 
 Person2:Sounds like a good idea . 
 Person1:        Okay . I'll pick you up at 6:00 . 
 Person2:Thank you for inviting me . See you then . Bye , Tom . 

informal