Code:
#include <iostream>
using namespace std;

class tacka
{     
      
      
      public:
             int x, y, z;
         tacka(int _x=0, int _y=0, int _z=0)
             {
                       x = _x;
                       y = _y;
                       z = _z;
             }
tacka(tacka & original)
             {
                        x = original.x;
                         y = original.y;
                         z = original.z;
                        
             } 
             
             
             friend tacka operator+ (tacka, tacka);

void info(){cout<<" "<<x<<" "<<y<<" "<<z<<endl;  }           
             
};

tacka operator+(tacka lijevi, tacka desni)
{
                      int x = lijevi.x + desni.x;
                      int y = lijevi.y + desni.y;
                      int z = lijevi.z + desni.z;
                      
                      tacka tmp(x, y, z);
                      
                      return tmp;
}


int main()
{
    tacka a(1,1,1);
    tacka b(2,2,2);
    
    tacka c = a+b;  // zasto ne moze ovako
   
    c.info();
    system("pause>0"); return 0;
}