#include <iostream>
 
class Base
{
public:
    virtual void whoAmI()
    {
        std::cout << "\nI'm base\n" ;     
    }       
};
 
class Derived : public Base
{
};
 
 
class SecondDerivative : public Derived
{
public:
    virtual void whoAmI()
    {
        std::cout << "\nI'm Second derivative\n" ;     
    }       
};
 
int main()
{
    SecondDerivative SD;
    Base* b = &SD;
    b->whoAmI();
 
    Derived d;
    b = &d;
    b->whoAmI();
    return 0;     
}

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