public class Main {
 
    static class Bird {
        int i = 11;
        Bird() {
            i++;
            Dog.printI(i);
            System.out.println("into bird");
        }
    }
    
    static class Dog {
        Bird bird = new Bird();
        Dog() {
            System.out.println("into dog");
            cat.eat();
        }
        static void printI(int i) {
            System.out.println(i);
        }
        static Cat cat = new Cat();
    }

    static class Cat {
        Cat() {
            System.out.println("into cat");
        }
        void eat() {
            System.out.println("l love eat fish");
        }
    }
    public static void main(String[] args) {
        System.out.println("just a test!");
        Dog dog1 = new Dog();
        Dog dog2 = new Dog();
        dog1.printI(9);
        System.out.println("test is over");
    }
}