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:       It's wonderful to be in the mountains after a hustle bustle week .  
 Person2:Indeed . I love the smell of the grass and trees . They certainly refresh my mind .  
 Person1:        Can we stop here for a while ? My backpack is very heavy .  
 Person2:Sure . Did you hear anything ? Look ! An eagle is hovering in the sky .  
 Person1:        Let me see . It's not an eagle . I think it's a vulture .  
 Person2:Yes . Will it hurt us ?  
 Person1:        I don't think so . Let's walk by the stream . I am sure we can find the waterfall on the map .  
 Person2:OK . I have a good pair of hiking boots . It should not be a big problem .  
 Person1:        I also brought a bottle of water and some provisions . If you are hungry , you can let me know .  
 Person2:You are kind . Look there is a big tree over there , it looks like a thousand-year-old tree .  
 Person1:        Well , it is a birch tree.It is not as old as you think .  
 Person2:How do you know ?  
 Person1:        Because its trunk is not thick enough to be like a thousand-year-old tree . 

informal