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:       I am thinking about inviting you to a dinner . When would you have time ? And what kind of food do you fancy ?  
 Person2:That would be great . I am really in the mood for a spicy hotpot . Any special reason for the invitation ?  
 Person1:        To thank you for helping me at work last week . If you would not have been so kind , I would not have been able to pick my parents from the airport . You really did me a big favor . Thank you so much .  
 Person2:It was my pleasure . How about this evening ? I feel very hungry now .  
 Person1:        Fine , I know a good hotpot place in the downtown area , food there is pretty spicy too . Shall we try that one ?  
 Person2:Ok with me . You are the boss . I will meet you downstairs after work . 

formal