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:       Is the lake very polluted ?  
 Person2:Well , I wouldn't swim in it - but the water is much cleaner than it was a few years ago .  
 Person1:        Are local factories allowed to discharge waste water into the lake ?  
 Person2:Yes , but it must be treated in an effluent treatment plant first . 

formal