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:       Mr . : Are you Mary Lin ? 
 Person2:Yes . 
 Person1:        Mr . : I'm Mr . Rogers , your homeroom teacher . 
 Person2:Where should I sit ? 
 Person1:        Mr . : Why don't you sit behind Brad ? 
 Person2:Who's Brad ? 
 Person1:        Mr . : He's that guy in the blue shirt . 
 Person2:When does the first period begin , by the way ? 
 Person1:        Mr . : As soon as the bell rings after the morning announcement . 

formal