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:       Good afternoon , Mrs . Brown . I've come to see Mr . Brown .  
 Person2:Good afternoon , Mr . Green .  
 Person1:        Is he in ?  
 Person2:I'm sorry , but he's not in , he's gone out on business .  
 Person1:        Oh ! I just drop in on him for a chat .  
 Person2:Please come in for a cup of coffee .  
 Person1:        No , thank you . Please tell him to phone me when he comes back . 

formal