public class ComplexNumber{
    private double real_part, im_part;

    public ComplexNumber(double re, double im){
	real_part = re;
	im_part = im;
    }

    public double getRealPart(){
	return real_part;
    }

    public double getImaginaryPart(){
	return im_part;
    }

    public ComplexNumber conjugate(){
	return new ComplexNumber (real_part, -im_part);
    }

    public double norm(){
	return Math.sqrt (real_part * real_part + im_part * im_part);
    }

    public ComplexNumber add(ComplexNumber w){
	double x,y;
	x = this.real_part + w.real_part;
	y = this.im_part + w.im_part;
	return new ComplexNumber (x,y);
    }

    public ComplexNumber subtract(ComplexNumber w){
	double x,y;
	x = this.real_part - w.real_part;
	y = this.im_part - w.im_part;
	return new ComplexNumber (x,y);
    }

    public ComplexNumber multiply(ComplexNumber w){
	double x,y;
	x = this.real_part * w.real_part - this.im_part * w.im_part;
	y = this.real_part * w.im_part + this.im_part * w.real_part;
	return new ComplexNumber (x,y);
    }

    public ComplexNumber divide(ComplexNumber w){
	ComplexNumber p = this.multiply(w.conjugate());
	double n = Math.pow(w.norm(),2);
	return new ComplexNumber (p.real_part / n , p.im_part / n);
    }

    public String toString(){
	if (im_part==0)
	    return real_part + "";
	if (real_part==0)
	    return im_part + "i";
	if (im_part > 0)
	    return real_part + " + " + im_part + "i";
	if (im_part < 0)
	    return real_part + " - " + (-im_part) + "i";
    }

    public double argument(){
	if (real_part>0) 
	    return Math.atan(im_part / real_part);
	if (im_part > 0 && real_part == 0)
	    return Math.PI/2;
	if (real_part<0 && im_part>=0)
	    return Math.PI + Math.atan(im_part/real_part);
	if (real_part<0 && im_part<0)
	    return -Math.PI + Math.atan(im_part/real_part);
	if (im_part<0 && real_part==0)
	    return - Math.PI/2;
    }
}