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:       I watched a very interesting documentary about plants yesterday evening . It was called “ unusual plants ” and looked at several species of plants from around the world which have unusual features .  
 Person2:Really ? Tell me about some of the plants they showed .  
 Person1:        Well . There was one type of plant that catches insects and eats them .  
 Person2:Is that type of plant found in this country ?  
 Person1:        No , it isn ’ t . it ’ s a pity , because I ’ d like to see it in action .  
 Person2:So would I . what other unusual plants did they show ?  
 Person1:        They showed flowers that only provide their nectar to one type of butterfly or bee . The insect has to be the exact size to get the nectar . Other insects cannot get it . Of course , when the insect collects the nectar , it also takes some pollen from one flower to another .  
 Person2:That ’ s very specialized . So , the insects and the flowers rely on each other . If one became extinct , the other would too .  
 Person1:        That ’ s right . That ’ s one reason why it ’ s so important to protect every species .  
 Person2:I see . The plants that fascinate me most are cacti . I find it amazing that they can survive in such dry desert conditions .  
 Person1:        According to the documentary , they have an incredible ability to find water supplies , however small , and then store them without losing much through evaporation .  
 Person2:That ’ s why they often have long roots to find water spines instead of leaves , to reduce water loss . 

informal