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:       Ten sheets of rice paper , 25 brushes , two boxes of oil color and two boxes of water color . All these come up to $ 35.50 , sir .  
 Person2:Ok , here is $ 50 . Oh , can you make out an invoice for me ?  
 Person1:        Sure , just a minute . Are you an artist , sir ?  
 Person2:No , I am a teacher . I teach art .  
 Person1:        That must be a very interesting job .  
 Person2:It is . You must be new here . I do my shopping here regularly , once a week .  
 Person1:        Do you ? Nice to meet you ! And here is the invoice and your change .  
 Person2:Thank you . Nice to meet you , too . 

informal