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:       Are these your text books ? Biochemistry , General Ecology , Botany , Cell Genetics , Molecular Genetics ... 
 Person2:Yes . I gotta review all of them for the final exam . It is just around the corner . 
 Person1:        Oh , right ! Do you have many exams at the end of each semester ? 
 Person2:That depends . Some semesters have many , some don't . And some courses don't have exams but only ask for papers . That's easy . 
 Person1:        And when do you prepare for your final exam ? 
 Person2:Honestly speaking , most students prepare it one month before the exam . 
 Person1:        Really ? You only review your lessons in one month ? Does it work ? 
 Person2:Of course , it's useful . And it's very crucial to have the copies of teacher's notes , because most questions in the exam are based on them . 
 Person1:        Wow , and all the key points are included in them ? You're so smart ! 
 Person2:But the exam is not as simple as you may imagine . We have to stay up late . 
 Person1:        Do you have the classrooms open for the whole night ? 
 Person2:Yes , some people even pack up his bed quilt and sleep there . That's a little bit crazy . 

informal