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:       When is your birthday ?  
 Person2:August 1st .  
 Person1:        Do you usually have a birthday party ?  
 Person2:Yes , we do.My parents prepare dinner for me .  
 Person1:        What would you do at the party ?  
 Person2:We sing " Happy Birthday " at the party and have birthday cakes .  
 Person1:        Do you know when people began to sing the song " Happy Birthday " ?  
 Person2:Well , I don't know .  
 Person1:        Let me tell you the story.In 1892 , Patty Smith Hill and Mildred Hill wrote a song called " Good Morning to you " . But later someone added the words " Happy Birthday " to their tune .  
 Person2:So the " Happy Birthday " song has been popular since then ?  
 Person1:        Yes , actually , the song has been sung since its publication in 1932.People all over the world have sung it in many different languages . 

formal