#include <iostream>
using namespace std;
class A
{
protected: int x;
public: A(int i = -16) { x = i; }
virtual A f(A a) { return x + a.x; }
void afisare() { cout << x; }
};
class B: public A
{
public: B(int i=3):A(i){}
A f(A a) { return x + 1; }
B operator+ (B a) { return x + a.x; }
};
int main()
{
B a; int b = -21;
a += b;
cout << b;
return 0;
}