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 very grateful for what you have done to my son , doctor .  
 Person2:That's all tight , Mr.Smith.That ' s my job . I'm very glad he recovered so soon .  
 Person1:        I know he has brought great trouble to you . A million thanks .  
 Person2:No trouble at all . He's very cute and brave . By the way , do remember to keep him away from sea food for at least two weeks .  
 Person1:        I will . It's most thoughtful of you . 

informal