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:       What can I do for you ? 
 Person2:I wish to buy a diamond ring . 
 Person1:        How many carats diamond do you want ? 
 Person2:Two carats . 
 Person1:        Is this one suit for you ? 
 Person2:No , it seems too old-fashioned . 
 Person1:        What about this ? 
 Person2:Let me try it on , it's too small for me , haven't you got any larger ones ? 
 Person1:        Yes , try this one please . 
 Person2:This fits me well , how much is it ? 
 Person1:        3,500 yuan . 
 Person2:It's reasonable . Here you are . 

informal