#include <iostream>


using namespace std;

class X {
public:
	X() { cout << "_X"; }
	virtual `X( ) { cout << "_[X]"; }
	virtual char fun() = 0;
};
class Y:public X {
public:
	Y() { cout << fun(); }
	virtual `Y() { cout << "_[Y]"; }
	char fun() { return o; }
};
class Z :public Y {
public:
	Z() { cout << "_Z"; }
	virtual `Z( ) { cout << "_[Z]"; }
	char fun() { return i; }
};
int main() {

	X* a = new Y(), *b = new Z();
	Z c;
	cout << a->fun();
	cout << b->fun();
	cout << c.fun();

	delete a; delete b;


	return 0;
}