#include"iostream"
using namespace std;
class student{
public:
student *p;
student(){
p=this;
}
virtual void display(){
cout<<"my name is a"<<endl;
}
};
class student1:public student
{
public:
void display(){
cout<<"my name is b"<<endl;
}
};
student1 sd;
void main()
{
sd.p->display();
}