#include<iostream>
#include<bits/stdc++.h>
using namespace std;
class A
{
    public:
        A(){cout<<"create A"<<endl;}
        virtual ~A(){cout<<"conustructing A"<<endl;}
        virtual void f(){cout<<"it's A "<<endl;}

};
class B:public A
{
    public:
        B(){cout<<"Create B"<<endl;}
        virtual~B(){cout<<"constructing B"<<endl;}
       virtual void f(){cout<<"it's B"<<endl;}
};
class C:public B
{
    public:
    C(){cout<<"Create C"<<endl;}
    ~C(){cout<<"constructing C"<<endl;}
    void f(){cout<<"it's C"<<endl;}
};
int main()
{
    A a, *p;
    B b ,*q;
    C c ,*r;
    p=&a;
    q=&b;
    r=&c;
    p->f();
    q->f();
    r->f();
    return 0;

}