OOP

#include <iostream>

using namespace std;

class A
{
public:
    A(){};
    void virtual move()=0;
};

class B1: public A
{
public:
    B1(){};
    void virtual move(){
        cout<<2<<endl;
    }
};
class B3: public A
{
public:
    B3(){};
    void virtual move(){
        cout<<3<<endl;
    }
};


int main()
{
    A* t;
    t = new A;
    t->move();
}