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:       In my opinions , someone else has caused the fire of this house .  
 Person2:Who do you think that has the motive ?  
 Person1:        I ’ m not sure now . In any case , let ’ s first make some careful investigations .  
 Person2:OK , murder will out !  
 Person1:        Yeah . 

formal