#include <iostream>
using namespace std;


class Base
{
    protected:
        int a, b;
    public:
      
        Base(int x, int y)
        {
            a = x;
            b = y;
        }
};


class Derived : public Base
{
    public:
      
        Derived(int x, int y) : Base(x, y)
        {
        }

     
        void swap()
        {
            int temp = a;
            a = b;
            b = temp;
        }

     
        void display()
        {
            cout << "a = " << a << endl;
            cout << "b = " << b << endl;
        }
};

int main()
{
    
    Derived d(10, 20);

   
    cout << "Before swapping:" << endl;
    d.display();

 
    d.swap();

  
    cout << "After swapping:" << endl;
    d.display();

    return 0;
}