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:       Would you like to go to the natural history museum with me ?  
 Person2:Have you ever been to it before ?  
 Person1:        Yes , lots of time . I was quite impressed by the wide variety of exhibitions they have .  
 Person2:Let's go . It sounds interesting . 

informal