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:       Hi , long time no see . How have you been ? 
 Person2:Oh , I've been fine , but I'm having some trouble with my son . 
 Person1:        Tell me all about it . 
 Person2:Oh , he's 14 and in the past few months , he's become quieter and a bit secretive . He locks himself in his room and I think he's running around with the wrong crowd . 
 Person1:        Oh , I see . What makes you think that ? 
 Person2:Well , he's become friends with a couple of older boys who are in a band . And one night last weekend , he came home really late , way past his curfew . 
 Person1:        Really ? What happened ? 
 Person2:He told me that his friend's car broke down and they had to walk home . 
 Person1:        I see what you mean . I understand why you're concerned . Have you tried talking to your son about it ? 
 Person2:I haven't yet . I just keep hoping it's just a phase he's going through . 
 Person1:        You may be right , but it doesn't hurt to find out more about what's going on in his life . 
 Person2:You're right . I should talk to him . Sometimes , it's not easy being a parent . Thanks . It helps to get it off my chest . You're always so easy to talk to . 
 Person1:        I don't know about that , but my door is always open . Stop by anytime . 

informal