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:       I'm afraid I've got to go . I have another appointment at five .  
 Person2:Do you ? By the way , could you mail this letter for me as you go through the lobby ?  
 Person1:        No problem .  
 Person2:Thank you . Come back to my office at the same time tomorrow . I'll have the pictures ready by then .  
 Person1:        I will . 

informal