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:       What ’ s “ pi ” ?  
 Person2:That ’ s the ratio of the circumference of a circle to its diameter , I think .  
 Person1:        I see . What is that ratio exactly ?  
 Person2:It ’ s approximately 3.14 , but the number continues forever . What ’ s the diameter of your circle ?  
 Person1:        It ’ s 10 centimeters , so the circumference should be 31.4 centimeters .  
 Person2:Ok . My next problem is to convert 10000 british pounds into us dollars . What ’ s the exchange rate at the moment ?  
 Person1:        According to the newspaper , the exchange rate is 1.85 dollars to the pound .  
 Person2:That means that 10.000 pounds will buy me 18.500 dollars .  
 Person1:        What ’ s the next question .  
 Person2:Fractions . What ’ s a quarter and an eighth ? That ’ s three-eights . Easy . The next question is “ what are prime numbers ? ” .  
 Person1:        I can help you there . Those are numbers that cannot be created by multiplying two whole numbers , apart from the number itself and 1 , together .  
 Person2:So , 1,2 and 3 are prime numbers , but 4 isn ’ t because 2 * 2 = 4 .  
 Person1:        Exactly . Anything else ?  
 Person2:How many seconds in an hour ? 60 seconds multiplied by 60 minutes equals 3600 seconds altogether .  
 Person1:        You ’ ll be a mathematician one day . 

formal