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:       There are things that are actually even smaller than atoms . 
 Person2:What are those ? 
 Person1:        They are the things that make up the atom , such as electrons and protons . 
 Person2:Is there anything that is smaller than electrons and protons ? 
 Person1:        Of course there is . Things can be divided and broken down into indefinitely small parts if we can . 
 Person2:I really don't want to know about this . Physics gives me a headache . 

informal