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:       Jack , I hear you got promoted.Is that true ? 
 Person2:Yes . I think I'm lucky . 
 Person1:        Oh , Jack , you deserve it.You ' Ve been working so hard . 
 Person2:Thank you for saying that . 

informal