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:       Can I help you , sir ?  
 Person2:I wish to buy a diamond ring .  
 Person1:        How many carats would you like it to be ?  
 Person2:I want five carats .  
 Person1:        Is this one suitable for you ?  
 Person2:No , it seems too old-fashioned to my fiancee .  
 Person1:        What about this ?  
 Person2:It seems too small for me , haven't you got any larger ones ?  
 Person1:        Then you can buy this one . It's very nice and latest in style .  
 Person2:Oh , this one is perfect . 

informal