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:       How about going to dance this evening , Jane ? You will find that the night life of this city is very interesting ! 
 Person2:Good idea . There is a good nightclub nearby , isn't it ? 
 Person1:        Yes , the dance hall is nice with various styles of music . 
 Person2:( In the club ) Look at those people in the dance floor , they are so crazy . 
 Person1:        That's rock and roll with fast tempo . 
 Person2:I like the slow dance . I am good at rumba and waltz . 
 Person1:        Take it easy . The time for slow dance is the middle part of the party . 
 Person2:Let's find a quiet seat and sit down for beverage . 
 Person1:        OK , follow me . 
 Person2:Listen , it is waltz . I like the elegant step of the old styles . 
 Person1:        May I ? 
 Person2:Sure . 
 Person1:        ( When they are dancing ) You dance gracefully ! 

informal