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:       Do you know that song ?  
 Person2:Which song ?  
 Person1:        The song you hear now .  
 Person2:No , I've never heard of this song before . It's beautiful ! Who sing it ?  
 Person1:        Elvis Presley . Don't you recognize his voice ?  
 Person2:No . How about going to karaoke tonight ?  
 Person1:        Good idea . 

informal