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:       Well , what a nice day !  
 Person2:Yeah , the air is really fresh .  
 Person1:        But it was not at all so fine yesterday .  
 Person2:Because it rained last night .  
 Person1:        Did it ?  
 Person2:It sure did . It was a heavy storm , with lots of thunder .  
 Person1:        I was fast asleep , and didn't hear a thing .  
 Person2:Well , it may rain again later today .  
 Person1:        Maybe . I see some dark clouds moving in .  
 Person2:There may also be a strong wind coming in .  
 Person1:        It'll be dusty , too , I guess .  
 Person2:Maybe not . Dust is no longer a big problem in Beijing .  
 Person1:        Why is that ?  
 Person2:We've been planting trees for many years .  
 Person1:        I see . The fall in Beijing is really beautiful .  
 Person2:But the summer isn't . It's scorching in the summer .  
 Person1:        Then what about spring ?  
 Person2:Spring is warm and short in Beijing .  
 Person1:        It must be cold in the winter , though .  
 Person2:You got it . Oh , by the way , it may be really cool in the evening around this time of the year . Don't forget to put on more clothes , or you might catch a cold .  
 Person1:        Thanks for reminding me .  
 Person2:You're welcome . 

informal