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 is night life in Beijing ?  
 Person2:Very interesting !  
 Person1:        What do you suggest then ?  
 Person2:How about going to dance ? There is a very good nightclub nearby .  
 Person1:        That's a great idea . Let's go ... Oh , the dance hall looks very nice and the music is wonderful .  
 Person2:I'm glad you like it.The band is called " Four and One " . They are especially good at playing rock and roll .  
 Person1:        That's great ! I love to dance to fast music .  
 Person2:Then you must be interested in disco dancing , aren't you ?  
 Person1:        Yes , disco dancing is my favorite.It ' s great fun and good exercise as well .  
 Person2:OK . Let's disco .  
 Person1:        Now the band is playing a slow dance .  
 Person2:That's a waltz . Would you like to try it ?  
 Person1:        Sorry , I think I'Il sit out the next dance .  
 Person2:All right . Let me get you something to drink . 

informal