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:       Anna , that outfit looks wonderful on you ! The color goes with your trousers perfectly .  
 Person2:Thanks , Carla . That's quite a compliment coming from you . You always dress so tastefully .  
 Person1:        Well , that dress certainly shows your good taste . It must have cost a lot .  
 Person2:No , not much . I got it on sale at the mall - 60 % off .  
 Person1:        Really ? You're an amazing bargain hunter ! Next time there's a sale , promise you'll let me tag along with you .  
 Person2:It's a promise . 

informal