Instructions: 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: Congratulations , Vivian . You won the grand prize , again .
Person2:Isn't it just great ! I just knew I'd win !
Person1: You did ? How ? Did you wear red underwear again this year ?
Person2:Not only that !
Person1: Tell me ! Tell me ! What's your secret ? !
Person2:OK , OK . I'll whisper it to you , but you have to promise not to tell anyone !
Person1: What ? ! You did that ? ? ! ! !
Output:
informal