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:       Excuse me , is this seat taken ?  
 Person2:Er ... no , go ahead .  
 Person1:        You work upstair , right ? I think I have seen you before . I'm Karren , Karren Brown .  
 Person2:Nice to meet you , Karren . I'm Tim Wang .  
 Person1:        Happy to know you , Tim . 

informal