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 , can you do me a favor ?  
 Person2:Sure .  
 Person1:        Where's the busiest street of this city ? I am a stranger here .  
 Person2:You mean the seventy seventh ? It's not far from here . You can walk there .  
 Person1:        Well , we are so tired today . Can you tell me which bus I should take ?  
 Person2:Bus No . 12 .  
 Person1:        Thank you so much . 

informal