#include<iostream.h>
class A
{
public:
	int va;
	A(int i){va=i;}
	virtual A& operator+(A&);
	virtual A& operator=(A&);
	virtual int a(){return va;}
	virtual int b(){return 0;}
	virtual int c(){return 0;}
	void disp(){cout<<"va="<<va<<endl;}
};
class B:public A
{
public:
	int vb;
	B(int i,int j):A(i){vb=j;}
	virtual A& operator+(A&);
	virtual A& operator=(A&);
	virtual int b(){return vb;}
	void disp(){cout<<"vb="<<vb<<endl;}
};
class C:public B
{
public:
	int vc;
	C(int i,int j, int k):B(i,j){vc=k;}
	virtual A& operator+(A&);
	virtual A& operator=(A&);
	virtual int c(){return vc;}
	void disp(){cout<<"vc="<<vc<<endl;}
};
A& A::operator+(A& t)
{
	va+=t.a();
	return *this;
}
A& A::operator=(A& t)
{
	va=t.a();
	return *this;
}
A& B::operator+(A& t)
{
	va+=t.a();
	vb+=t.b();
	return *this;
}
A& B::operator=(A& t)
{
	va=t.a();
	vb=t.b();
	return *this;
}
A& C::operator+(A& t)
{
	va+=t.a();
	vb+=t.b();
	vc+=t.c();
	return *this;
}
A& C::operator=(A& t)
{
	va=t.a();
	vb=t.b();
	vc=t.c();
	return *this;
}
void addobject(A& ob1,A& ob2)
{
	ob1=ob1+ob2;
}
void main()
{
	A a(10);
	B b(20,30);
	C c(40,50,60);
	addobject(a,b);
	addobject(b,c);
	addobject(c,b);
	a=b+c;
	c=c+a;
	a.disp();
	b.disp();
	c.disp();
}