#include <iostream>
#include <string>
using namespace std;

/**
 * Base class
 */
class Person {
protected:
	string name;
	int age;
public:
	// default constructor
	Person() {
		name = "";
		age = 0;
	}
	
	// constructor with 2 arguments
	Person(string n, int a) {
		name = n;
		age = a;
	}
		
	// display class
	virtual ostream& print(ostream& out) {
		out << name << ", " << age;
		return out;
	}
	
	friend ostream& operator<<(ostream& out, Person& p) {
		return p.print(out);
	}
};

/**
 * Inherited class with redefinition of virtual method print
 */
class Student : public Person {
protected:
	string level;
	
public:	
	Student(string n, int a, string l) : Person(n, a), level(l) {
	}
	
	ostream& print(ostream& out) {
		Person::print(out);
		out << ", level = " << level;
		return out;
	}
};

int main() {
	Person p("toto", 10);
	Student s("john", 20, "l3 informatique");
	
	cout << p << endl;
	cout << s << endl;
	
	return 0;
}