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:       Hello , this is Helen speaking .  
 Person2:Hello , Helen . This is John . How are you ?  
 Person1:        Fine , thank you . And you ?  
 Person2:Fine , thanks . I ’ ll have a party next Sunday at home . I ’ m calling to ask whether you can come or not .  
 Person1:        Oh , how wonderful . I ’ ll be glad to .  
 Person2:Okay , now you are a famous star .  
 Person1:        Hum , don ’ t say that . Maybe you can do something useful for me .  
 Person2:What ’ s wrong with you ?  
 Person1:        I ’ ll tell you at the party .  
 Person2:Okay . 

informal