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 would back him up to the hilt anyway . 
 Person2:Why are you so kind to him ? 
 Person1:        He's my brother . 
 Person2:So that's how it is ! Now he ’ s in trouble , but I belive he will rise to his own feet again . 
 Person1:        Thanks for your belief . 

informal