#include <iostream>
using namespace std;


class Base {
//no visitbility means private, not visible for derived
protected:   // this is visible for derived, but not for outsiders
    int x, y; 
public:      // this is visible for everyone
    virtual void readDataFromStream(istream&);
};  

void Base::readDataFromStream(istream& is) {
    //insert values from stream into attributes
    is >> x;
    is >> y;
    cout <<"done-";
}

class Derived :  Base {  // no inheritance visibility: outside world don't have access to base pubic members
                         // if you want benefit from inheritance, make it Derived: public Base
    //declaration
    //method inherited from Base
    int z; 
public: 
    void readDataFromStream(istream&) override;

    //definition - overrides definition in Base
    //function called from inside function that passes file data into stream
    //- stream already contains data
};

void Derived::readDataFromStream(istream& is) {
        //insert values from stream into attributes
    Base::readDataFromStream(is); 
    is >> z;
    cout << "yes";
}



int main() {
	// your code goes here
	Derived d; 
	
	d.readDataFromStream(cin); 
	return 0;
}