class A
{
public:
    ~A() {}
    virtual int e() = 0;
};

class B : virtual public A
{
public:
    ~B() {}
    virtual int f() = 0;
};

class C : virtual public A
{
public:
    ~C();
    C(int a);
protected:
    int _c;
    virtual int e();
};

class D : public C, virtual public B
{
public:
    ~D();
    D(int a);
    virtual int f();
};

C::C(int a)
{
    _c = a;
}

C::~C()
{
}

int C::e()
{
    return _c;
}

D::D(int a):C(a)
{
}

D::~D()
{
}

int D::f()
{
    return _c+1;
}

int main()
{
    D* d = new D(1);
    delete d;
}