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:       How ’ s your trip going ?  
 Person2:Oh I ’ m enjoying myself but it ’ s so hot here  
 Person1:        Isn ’ t London hot in the summer ?  
 Person2:Well it can be but Shanghai is much warmer than London .  
 Person1:        I see . What about transport ? How does Shanghai compare to London ?  
 Person2:Actually I think the buses and trains here are more modern .  
 Person1:        And what about the number of people on the streets ?  
 Person2:Oh , I think Shanghai is much more crowded than London . 

informal