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:       Would you like a piece of birthday cake ?  
 Person2:No , thanks , I'll pass . It looks very tempting though .  
 Person1:        I thought strawberry cake with cream cheese frosting was your favorite ?  
 Person2:It is . I'm on a diet and strawberry cream cheese cake is not on it .  
 Person1:        A diet ? What for ? You are in great shape .  
 Person2:I went to the doctor the other day . My cholesterol is up .  
 Person1:        Oooo . This sounds serious .  
 Person2:Not too serious . But he gave me a strict diet to help bring it down . 

informal