How to derived operator >> from Base class !

Simple trick :
D ! Have fun !

#include <iostream>

class Base    
{    
protected :
    int x;
public :
    friend std::istream &operator >>( std::istream &is, Base &b )
    {
        is >> b.x;
        return is;
    }
};



class Derived : public Base
{
private :
    int y;

public :
    friend std::istream &operator >>( std::istream &is, Derived &d )
    {
        is >> static_cast< Base & >( d );
        is >> d.y;
        return is;
    }
};


int main()
{
    Derived d;
    std::cin >> d;

    return 0;
}