Implement the following two Java classes. Zn encapsulates the elements of the ring Zn, integers modulo n. Complex encapsulates the complex numbers.

public class Zn extends Ring {

public static int n;

// construct a Zn element from integer

public Zn(int a)

// return a string in the form [3]

public String toString() }

public class Complex extends Field {

// construct the complex number x + yi

public Complex(double x, double y)

// return a string in the form -3+4i

public String toString()

}

The Ring and Field classes are defined as:

public abstract class Ring {

public abstract Ring add(Ring other);

public abstract Ring sub(Ring other);

public abstract Ring mul(Ring other);

}

public abstract class Field extends Ring

{

public abstract Field div(Field other);

}