class Animal{
public:
  Animal() {
    age = 0;
  }
  virtual ~Animal(){}
  static Animal* factory(int type);
  int aliveSince(){
    return age;
  }
  virtual int fly(int m){} //error, needs a return value
  virtual int swim(int m){} //error, needs a return value

private:
  int age;
};

class Bird: public Animal{
public:
  Bird(){
    totalFlight = 0;
  }
  int fly(int m){
    cout<<"Bird flew "<<m<<" metresn";
    return totalFlight = totalFlight+m;
  }
private:
  int totalFlight;
};

class Fish: public Animal{
public:
  Fish(){
    totalSwim = 0;
  }
  int swim(int m){
    cout<<"Fish swam "<<m<<" metres undergroundn";
    return totalSwim = totalSwim + m;
  }
private:
  int totalSwim;
};

Animal* Animal::factory(int type){
    if (type) return new Bird();
    else return new Fish();
}

Animal *a = Animal::factory(1); //Bird
Animal *b = Animal::factory(0); //Fish
a->aliveSince();
b->aliveSince();
a->fly(5);
b->swim(5);

virtual int fly(int m){ return 0; }
virtual int swim(int m){ return 0; }

class Animal{
public:
  Animal()
  {
    totalMoved = 0;
  }
  virtual ~Animal(){}
  virtual int move( int m )
  {
    totalMoved += m;
    cout<<"Total distance " << totalMoved << std::endl;
    return totalMoved ;
  }

protected:
  int totalMoved;
};

class Bird: public Animal{
public:
  int move(int m)
  {
    cout<<"Bird flew "<<m<<" metresn";
    return Animal::move( m );
  }
};

class Fish: public Animal{
public:
  int swim(int m){
    cout<<"Fish swam "<<m<<" metres undergroundn";
    return Animal::move( m );
  }
};