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 you show me some jade , please ?  
 Person2:Yes , of course . Do you like a jade necklace ?  
 Person1:        No , but I do like jade bracelets .  
 Person2:Here are all kinds of jades . Choose whatever you like , please .  
 Person1:        Thank you . ( A moment later ) Oh , this one is quite impressive . I'll take it . By the way , do you sell pearl earrings ?  
 Person2:Yes . Natural pearls or cultured pearls ? We have both kinds .  
 Person1:        I wonder which looks more lustrous .  
 Person2:Well , natural pearls are of higher value , but the cultured pearls have equal lustre and are just as beautiful .  
 Person1:        Oh , I see . I think I prefer a natural one . 

informal