#include <iostream>
using namespace std;

class A
{
 public: A() {cout << "A ";}
};

class B: virtual public A
{
 public: B() {cout << "B ";}
};

class C: virtual public A
{
 public: C(): A() {cout << "C ";}
};

class D: virtual public B, virtual public C
{
 public: D(): C(), B() {cout << "D ";}
};

/*
class E: public D
{
 public: E(): B() {cout << "E ";}
};
class F: virtual public E 
{
 public: F() {cout << "F ";}
};

//first easy example: prints A B C D E F 
*/

/*
class F: public B, virtual public C 
{
 public: F() {cout << "F ";}
};

//harder one: prints A C B F 
*/

/*
class E: public B
{
 public: E() {cout << "E ";}
};

class F: public E, virtual public C
{
 public: F() {cout << "F ";}
};

//hmmm: prints A C B E F 
*/

class E: virtual public B 
{
 public: E() {cout << "E ";}
};

class F: public E, virtual public C 
{
 public: F() {cout << "F ";}
};
// this one is crazyness: prints A B C E F

main()
{
 F f;
}