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:       Good evening , sir .  
 Person2:May I have the key for Room 358 , please ?  
 Person1:        Certainly . Oh , you have a message here .  
 Person2:Thank you . Is there any mail for me ?  
 Person1:        No , there isn't at the moment . 

formal