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: Consider Input: Person1: Charles , have you finished your homework ?
Person2:Not yet , Grandma , What's the matter ?
Person1: I want you to have a walk with me .
Person2:I'll finish soon .

Output: formal

Input: Consider Input: Person1: Will you bring our bill , please ?
Person2:Yes , certainly . I'll be back in a minute . Here you are
Person1: Thanks.Let me see . I think there's a mistake on the bill here.Would you mind checking , please ?
Person2:Of course , not.Let me check.Oh , you seem bo be correct .
Person1: How about tax and service charge ?
Person2:Only ten percent tax is included in the bill .
Person1: Then one hundred U . S . dollars covers everything , doesn't it ?
Person2:It sure does .

Output: informal

Input: Consider Input: Person1: What's your favorite book ?
Person2:It's Gone With the Wind .
Person1: Why do you like it best ?
Person2:I enjoy the various characters and the plot .
Person1: Well . I like the Thorn Birds best .
Person2:Is it very interesting ?
Person1: Sure . I like the writer's language , too .
Person2:If I have a chance , I'll enjoy the book .
Person1: Would you like to go to the bookshop with me ?
Person2:That's a good idea . Let's go !
Output: informal