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:       The final examination will be held at the end of this month . Have you made good preparation ?  
 Person2:Sure . I've reviewed all the lessons I have learned this academic year .  
 Person1:        Are you sure you can do well this year ?  
 Person2:I am 100 % certain .  
 Person1:        According to what you did last time , I have my doubts .  
 Person2:I am sure I can get a 95 this time . 

formal