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'm sorry to interrupt you . Please take care not to make a mess while you are selecting goods . If you don't want it , please replace it . 
 Person2:Oh , I'm terribly sorry . but I couldn't find the yoghurt I saw here last time . 
 Person1:        What's the brand ? 
 Person2:San Yuan . 
 Person1:        Oh , it's out of stock at the moment . Why don't you choose another brand instead ? 
 Person2:I'm not used to other brands . 
 Person1:        You can have a try . Maybe you will like it . 
 Person2:OK . I hope so . 

informal