class Base {
public:
    Base() { x = 0;  y = 0; }

    Base(int a, int b) {
        x = a;
        y = b;
    }

    Base(const Base& other) {
        x = other.x;
        y = other.y;
    }

    ~Base() {
        x = 0;
        y = 0;
    }

protected:
    int x;
    int y;
};

class Derived : public Base {
public:
    Derived() : Base()  {}

    Derived(int a, int b)
        : Base(a, b)  {}

    Derived(const Derived& other)
        : Base(other)  {}

    int add() { return (x + y); }

    int sub() { return (x - y); }
};

int main()
{
    Derived d(1, 2);

    cout << d.add() << endl;
    cout << d.sub() << endl;

    return 0;
}