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:       To be frank , I find philosophy rather boring . 
 Person2:To tell you the truth , it's the most tedious course i have ever had . 
 Person1:        How could you manage to pass the exam ? 
 Person2:It is still a mystery to me . 

informal