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:       But the auction is a blast ! And I haven't even told you the best part yet !  
 Person2:I don't care what the best part is . Whatever you say won't change my mind . I'm not buying anything !  
 Person1:        That stamp you've been looking for is for sale .  
 Person2:The 1879 Large Dragon ? Are you serious ? How much ?  
 Person1:        Hey ! I thought you weren't interested ! Sorry , I've gotta go ! I'm going to switch over to eBay and see if my bid is still the highest . 

informal