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:       May , is this the Hall of Ancient China ?  
 Person2:Yes . Look at these historical relics here , amazing !  
 Person1:        Why are they all in glass boxes ?  
 Person2:For protection . Some relics will turn to dust if exposed to air .  
 Person1:        So there isn't air in the glass boxes ?  
 Person2:No , there isn't . There is a vacuum in every box .  
 Person1:        I wonder how old these things are . Thousands of years ?  
 Person2:Yeah , they all come from a very ancient time .  
 Person1:        Hey , look at the tripod . I've seen it on TV .  
 Person2:It was made 4,000 years ago . It's priceless ! 

informal