#include <iostream>
#include <cmath>
using namespace std;

class Complex
{  
  double re, im;
 public:
  Complex ()  {}
  Complex (double, double);
  ~Complex () {}

  double modul ();
  Complex operator+  (Complex);
  Complex operator+= (Complex);
};

Complex::Complex (double a, double b) {
  re = a;
  im = b;
}

double Complex::modul () {
  return  sqrt(re*re + im*im) ;
}

Complex Complex::operator+ (Complex z2) {
  Complex temp;
  temp.re = re + z2.re;
  temp.im = im + z2.im;
  return temp;
}

Complex Complex::operator+= (Complex z2) {
  re += z2.re;
  im += z2.im;
  return *this;		//  this: wskaznik na wlasny obiekt.
}			// *this: tenze wlasny obiekt.


/* Uwaga: jezeli dzialanie operatora+= ma sie ograniczyc tylko do instrukcji typu
          a += b;
          to mozna jeszcze uproscic:
  
   void Complex::operator+= (Complex z2) {
     re += z2.re;
     im += z2.im;
   }
*/


int main () {
  Complex z1 (3,4);
  cout << "|z1| =  " << z1.modul() << endl;

  Complex z2 (-2, -3);
  Complex z3 = z1 + z2;
  z3 += z1;
  cout << "|z1+z2| = " << z3.modul() << endl;

  return 0;
}