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'.

Ex Input:
Person1: Our philosophy teacher is very humorous .
Person2:I usually have the wrong notion that he's very serious .
Person1: No , not at all.The examples he gives are very interesting .
Person2:No wonder when I pass your room , I always hear your laughter .

Ex Output:
informal

Ex Input:
Person1: Would you like to come over for dinner tonight ?
Person2:Sure , but I have to tell you that I've become a vegetarian . I don't eat any kind of meat .
Person1: When did you decide to become a vegetarian ?
Person2:I saw a program a few months ago about how animals are raised for human consumption . I haven't been able to eat a single piece of meat since .
Person1: That's great . Do you find that you eat a lot more fruit and vegetables now ?
Person2:Definitely . I've also been buying organic fruit and vegetables , which is more expensive , but much better for you because they don't have any pesticides on them .
Person1: You've really turned into a health nut , haven't you ?
Person2:I guess you could say that . Eating fruit and vegetables helps keep you healthy . I've lost 5 pounds and I feel great !
Person1: How do you get enough protein in your diet ?
Person2:Well , I eat a lot more tofu , beans , nuts and some fish .
Person1: Well , don't worry about dinner . I'll only make vegetarian dishes for you . Do you like sushi ?
Person2:I prefer cooked fish to raw fish , but if you really like it , make it .
Person1: How about a spicy tofu and vegetable stir-fry ?
Person2:That sounds great . What time should I come over ?
Person1: Dinner will be ready at about 7:30 pm , so you can come over at 7 p . m .
Person2:Sounds good . See you there !

Ex Output:
informal

Ex Input:
Person1: Would you mind going to dinner with me tonight ?
Person2:I'd love to go out with you , but I'm sorry I'm busy tonight , but I'd like a rain check .
Person1: OK .

Ex Output:
informal