#include <iostream>

using namespace std;

class Rational {
  public:
    Rational(int n=0, int d=1) : n_(n), d_(d) {}

    int num() const {return n_;}
    int den() const {return d_;}

    ostream& operator<<(ostream&);
  private:
    int n_, d_;

    //friend ostream& operator<<(ostream&, const Rational&);
};

// ostream& operator<<(ostream& out , const Rational& r) {
//   out << r.n_ << "/" << r.d_;
// }

ostream& Rational::operator<<(ostream& out) {
  return out << n_ << "/" << d_;
}

int main() {
  Rational r1(10);
  Rational r2(3,5);

  // cout << "r1 " << r1<< endl;
  // cout << "r2 " << r2<< endl;

  r1 << cout << endl;
  r2 << cout << endl;

}