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:       Sir , your hair is done . Anything else I can do for you ?  
 Person2:I'd like to have a shave .  
 Person1:        All right , sir . Would you lie back so that I can shave you ?  
 Person2:Sure . But my beard is rough .  
 Person1:        Don't worry , sir . I've never cut a customer . Shall I trim your moustache ?  
 Person2:Yes , please .  
 Person1:        Now , I've finished . How do you like it ?  
 Person2:Wonderful . How much is the cost altogether ?  
 Person1:        20 dollars .  
 Person2:Here you are . Thank you , bye-bye !  
 Person1:        Bye-bye . Welcome to come next time ! 

informal