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:       Happy Birthday , Mary !  
 Person2:Thank you .  
 Person1:        Here is a gift for you . I hope you like it .  
 Person2:What a lovely dog ! How did you know I love this ?  
 Person1:        I had my own ways of finding out . It's a secret . You look so beautiful today . Your new shirt goes well with your skirt .  
 Person2:Maybe you don't believe it , but it was made by my grandmother .  
 Person1:        Really ? It looks so nice .  
 Person2:Thank you . Please have a cup of tea .  
 Person1:        All right .  
 Person2:How about some fish ?  
 Person1:        No , thanks . I've had enough . Now , Mary , before you blow out the birthday candles , you have to make a wish . After that , you may cut the cake .  
 Person2:OK , let me make a wish ... Do you want a big piece of cake ?  
 Person1:        No , just a small one . Next let's sing ' Happy Birthday ' to Mary .  
 Person2:It is very kind of you . I'm so moved by you . 

informal