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:       Oh , what a pleasant surprise ! Don't you remember me ?  
 Person2:Mr.Black , if I'm not mistaken .  
 Person1:        Right ! Glad to see you here .  
 Person2:Pleased to see you.too . 

informal