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:       Is this Zhang Lin's home ?  
 Person2:Yes.Oh , it's you , Linda . I haven't seen you for a long time.Well , come in and sit down.How about something to drink ?  
 Person1:        Yes , please . I'm a little thirsty , actually .  
 Person2:Would you like tea or coffee ?  
 Person1:        Coffee , please .  
 Person2:Here you are .  
 Person1:        Would you like to talk over a drink ?  
 Person2:That sounds good . How are you doing , Linda ?  
 Person1:        Just fine.Are you busy now ?  
 Person2:No . I'm just killing time .  
 Person1:        Shall we visit our math teacher tomorrow ?  
 Person2:Yes . I haven't been in his house for several weeks.When shall we start ?  
 Person1:        How about eight o'clock tomorrow morning ?  
 Person2:All right . See you tomorrow . 

informal