#include<iostream.h>
#include<conio.h>
class A
{
         public:
         void showA()
         {
                  cout<<"This is Class A";
          }
};
class B:virtual public A
{
       public:
       void showB()
       {
                  cout<<"This is class B";
        }
};
class C:virtual public A
{
       public:
       void showC()
       {
             cout<<"This is class C";
       }
};
class D:public B,pubic C
{
       public:
       void showD()
      {
            cout<<"This is class D";
      }
};
void main()
{
       D D1;
       D1.showA();
       D1.showB();
       D1.showC();
       D1.showD();
       getch();
}

OUTPUT;

This is class A
This is class B
This is class C
This is class D