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:       Good evening , sir . What's your pleasure this evening ? Your usual ?  
 Person2:Yes . I'm going to stay with the same , a beer .  
 Person1:        Certainly , a beer . Here you are , sir .  
 Person2:Oh , darn . Look what I've done . ( Spill the drink )  
 Person1:        Don't worry . I'll make you another on the house . 

informal