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 time flies !  
 Person2:Bill and Betty have already grown up .  
 Person1:        I can still remember our first date .  
 Person2:Look at that big tree over there .  
 Person1:        Yeah , oh my god ! It ’ s still there . We have our first date right on there .  
 Person2:Do you know that I fell in love with you at the first sight then ?  
 Person1:        You seemed to be dull at that time .  
 Person2:But you agreed to go out with me at last .  
 Person1:        ( Smile ) I can ’ t believe this for it ’ s been 20 years since we got married .  
 Person2:So do you feel happy now ?  
 Person1:        I couldn ’ t have been any happier !  
 Person2:Of course , we are the happiest family in the world . 

informal