#include <iostream>
using namespace std;

class Base {
    public:
        void display() {
            foo();
        }
        virtual void foo() {
            cout << "Base.foo()" << endl;
        }
    };
    
    class Derived : public Base {
    public:
        void foo() {
            cout << "Derived.foo()" << endl;
        }
    };
    
int main() {
    Derived* derived = new Derived();
    derived->display();
}