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'.

Example Input: Person1: Shall we go for a drive today ?
Person2:It feels like there's going to be rain later .
Person1: Maybe you're right .
Person2:We'll go tomorrow .
Example Output: informal

Example Input: Person1: What's wrong with him ?
Person2:His nose is out of joint because we forgot to invite him to the party .
Example Output: formal

Example Input: Person1: Bill , Happy Halloween !
Person2:Happy Halloween ! What creature are you going to dress up as ?
Person1: I will dress up as a vampire with big fangs .
Person2:May I have a look at your costume ?
Person1: Sure . Wait a moment . ( Several minutes later ) Here you are .
Person2:I like your black clothes and your fangs are cool .
Person1: I will bite many beautiful girls on the neck tonight . Maybe I will suck their blood .
Person2:Haha . Wish you good luck .
Example Output:
informal