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:       Excuse me , which one is of the highest quality here ? 
 Person2:This one . It is of the best quality and excellently tailored as well . You may try it on . 
 Person1:        That is nice . But I don't quite like the collar . 
 Person2:The collar ? It is just the collar that is popular with young people in Shanghai . 
 Person1:        I don't care what others wear . How much is it ? 
 Person2:250 Yuan . 
 Person1:        Really ? Too expensive . I don't think I can afford it . 
 Person2:But it is really worthwhile . 
 Person1:        OK , anyway , let me have it . 
 Person2:Here you are . 
 Person1:        Thank you . 

informal