#include <iostream>
#include <string>
using namespace std;

class abstraction_imp
{
public:
    virtual ~abstraction_imp(){}
    virtual void operation() =0;
};

class abstraction
{
public:
    virtual ~abstraction(){}
    virtual void operation() =0;
protected:
    abstraction(){}
};

class refined_abstraction : public abstraction
{
public:
    refined_abstraction(abstraction_imp *imp):_imp(imp){}

    void operation()
    {
        _imp->operation();
    }

private:
    abstraction_imp *_imp;
};

class concrete_abstraction_impA : public abstraction_imp
{
public:
    void operation()
    {
        cout << "concrete_abstraction_impA::operation"<<endl;
    }
};

class concrete_abstraction_impB : public abstraction_imp
{
public:
    void operation()
    {
        cout << "concrete_abstraction_impB::operation"<<endl;
    }
};

int main()
{
    abstraction *a = new refined_abstraction(new concrete_abstraction_impB);
    a->operation();
    delete a;
    return 0;
}