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:       Mom , happy Mother's Day ! A necklace for you .  
 Person2:What a surprise ! This is the best present I've ever received .  
 Person1:        Thank you for your love and care over the years . I love you so much .  
 Person2:I love you , too .  
 Person1:        How about a dinner tonight ? My treat .  
 Person2:Actually , I prefer to eat at home , and then we'll have more time to have a chat .  
 Person1:        All right . Let me prepare the supper . 

informal