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 I make preservation now ? 
 Person2:Sure . At what time ? 
 Person1:        9:45 , please . We want a table next to the window . 
 Person2:I am sorry , sir . We are booked until 9:10 . 
 Person1:        In that case , please help us reserve a table for 4 at 9:00 . 

informal