import tester.*;

interface IAnimal {
}

class Snake implements IAnimal {
	String name;
	int weight;
	String food;
	Snake(String name, int weight, String food) {
		this.name = name;
		this.weight = weight;
		this.food = food;
	}
	
}

class Dillo implements IAnimal {
	int weight;
	boolean isAlive;
	Dillo(int weight, boolean isAlive) {
		this.weight = weight;
		this.isAlive = isAlive;
	}
}

class Posn {
	int x;
	int y;
	Posn(int x, int y) {
		this.x = x;
		this.y = y;
	}
}

class Ant implements IAnimal {
	double weight;
	Posn location;
	Ant(double weight, Posn location) {
		this.weight = weight;
		this.location = location;
	}
}

interface IGrade {
}

class NoGrade implements IGrade {
	NoGrade() { }
}

class NumberGrade implements IGrade {
	int grade;
	NumberGrade(int grade) {
		this.grade = grade;
	}
}

class Examples{
  	Dillo rolly = new Dillo(2, true);
  	Ant suzy = new Ant(0.0001, new Posn(3, 4));
  	IAnimal fred = new Snake("Fred", 10, "cereal");
  	IAnimal friend = suzy;
  	// Ant yourFriend = friend;  //-- not ok
  	IGrade g1 = new NoGrade();
  	IGrade g2 = new NumberGrade(100);
}