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:       I've just got a new printer . How often do I need to replace the print heads ?  
 Person2:Well , under normal conditions each head lasts about 5 000 copies or so . It depends on the user , but about once a month is average .  
 Person1:        So if I don't print out very much , it could last a lot longer ?  
 Person2:That's right . It could last six months or more . This model's designed for heavy use . Don't worry - you'll get an error message telling you when to change the head . 

formal