text: #include <iostream>
  
  using namespace std;
  
  class Base
  {
  protected:
      int x;
  public:
      Base(): x(0){}
  };
  
  class Derived : public Base
  {
  private:
      int y;
  
  public:
      Derived() : y(0) {}
      void foo()
      {
          cout << x << y << endl;
      }
  };
  
  int main()
  {
      Derived obj;
      obj.foo();
  }
  
  /*
  00
  */