#include"iostream"
using namespace std;
class base
{
public:
    virtual void print() { cout << "base" << endl; }
};
class derived :public base
{
public:
    void print() { cout << "derived" << endl; }
};
void display(base *p, void(base::*pf)())
{
    (p->*pf)();
}
int main()
{
    derived d;
    base b;
    display(&d, &base::print);
    display(&b, &base::print);
    return 0;
}