// 在下面基类Base和派生类Derived中增加成员函数show，使得程序运行结果如下：
// Base
// Derived

#include <iostream>
using namespace std;
class Base {
public:
    // _________________________;

    virtual void show() {
        cout << "Base" << endl;
    }
};

class Derived : public Base {
public:
    // __________________________;

    virtual void show() {
        cout << "Derived" << endl;
    }
};

int main() {
    Base b, *ptr;
    Derived d;
    ptr = &b;
    ptr->show();
    ptr = &d;
    ptr->show();
    return 0;
};