Guinea Pig

import java.util.Scanner;

public class GuineaPig {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        double food = Double.parseDouble(scanner.nextLine());
        double hay = Double.parseDouble(scanner.nextLine());
        double cover = Double.parseDouble(scanner.nextLine());
        double weight = Double.parseDouble(scanner.nextLine());

        double foodGr = food * 1000;
        double hayGr = hay * 1000;
        double coverGr = cover * 1000;
        double weightGr = weight * 1000;

        int days = 1;
        while (days <= 30) {

            foodGr -= 300;

            if (days % 2 == 0) {
                hayGr -= (foodGr * 5) / 100;
            }
            if (days % 3 == 0) {
                coverGr -= weightGr * 0.3333;
            }
            days++;
        }
        double foodKg = foodGr / 1000;
        double hayKg = hayGr / 1000;
        double coverKg = coverGr / 1000;

        if (foodKg >= 0 && hayKg >= 0 && coverKg >= 0) {
            System.out.printf("Everything is fine! Puppy is happy! Food: %.2f, Hay: %.2f, Cover: %.2f.",
                    foodKg, hayKg, coverKg);

        } else if (foodKg < 0 || hayKg < 0 || coverKg < 0) {
            System.out.println("Merry must go to the pet store!");
        }
    }
}