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 . I'm leaving . Here is my key . 
 Person2:Just one second , sir , and I'll give you your receipt . Here you go . 
 Person1:        Thank you very much . 
 Person2:Sir , did you enjoy your stay here ? 
 Person1:        Well , most of my time here was pleasant . And New York itself is fantastic . 
 Person2:I'm glad you enjoyed the city , anyway . But please don't think too unkindly of us . 

informal