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 , Bobby , It seems that I can't arrive at your home by 12 o'clock .  
 Person2:What happened ? We're all expecting you , Hans , Dick , Archie ...  
 Person1:        I'm so sorry , I've been held up by the damn traffic jam for half an hour . I'd have arrived but for that .  
 Person2:I see . Where are you now , Li ?  
 Person1:        Thirty meters ahead is the Waterloo Bridge .  
 Person2:It's not far away from home , It's - let me see – about 20 minutes'walk , Can you walk here ?  
 Person1:        I've thought of that , but what can I do with my car ? If only I had taken a taxi !  
 Person2:That's too bad , But don't worry.We ' ll put off dinner till one o'clock .  
 Person1:        I'm so terribly sorry to keep you waiting .  
 Person2:It doesn't matter.Bye .  
 Person1:        Bye . 

formal