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:       How are you tonight , sir ?  
 Person2:Oh , not too bad . I'm just glad the weekend's finally here .  
 Person1:        I know what you mean . What can I get for you ?  
 Person2:Give me a screwdriver on the rocks .  
 Person1:        One screwdriver , coming right up . ( He mixes the drink . ) Here you are , sir .  
 Person2:Thanks . 

informal