// Written in ENGR 131, 11/08/07

public class Complex {
  private double realPart, imagPart;
  
  public Complex(double a, double b) {
    realPart = a;
    imagPart = b;
  }
  
  public Complex() {
    realPart = 0.0;
    imagPart = 0.0;
  }
  
  public void print() {
    System.out.printf("( %f, %f)\n", realPart, imagPart);
  }
  
  // class method
  public static Complex add(Complex c1, Complex c2) {
    Complex c3 = new Complex();
    c3.realPart = c1.realPart + c2.realPart;
    c3.imagPart = c1.imagPart + c2.imagPart;
    return c3;
  }
  
  // instance method
  public Complex add(Complex that) {
    Complex ans = new Complex();
    // System.out.print("1st arg: ");
    // this.print();
    // System.out.print("2nd arg: ");
    // that.print();
    ans.realPart = this.realPart + that.realPart;
    ans.imagPart = this.imagPart + that.imagPart;
    // System.out.print("answer : ");
    // ans.print();
    return ans;
  }
  
  // class method
  public static Complex subtract(Complex c1, Complex c2) {
    Complex c3 = new Complex();
    c3.realPart = c1.realPart - c2.realPart;
    c3.imagPart = c1.imagPart - c2.imagPart;
    return c3;
  }
  
  // instance method
  public Complex subtract(Complex that) {
    Complex ans = new Complex();
    // System.out.print("1st arg: ");
    // this.print();
    // System.out.print("2nd arg: ");
    // that.print();
    ans.realPart = this.realPart - that.realPart;
    ans.imagPart = this.imagPart - that.imagPart;
    // System.out.print("answer : ");
    // ans.print();
    return ans;
  }
}