перегрузка дроби

#include <numeric>
#include <algorithm>
#include <cmath>
#include <iostream>
#include <map>
#include <set>
#include <string>
#include <utility>
#include <vector>

using namespace std;

class Rational {
public:
    Rational() = default;

    Rational(int numerator)
        : numerator_(numerator)
        , denominator_(1) {
    }

    Rational(int numerator, int denominator)
        : numerator_(numerator)
        , denominator_(denominator) {
        Normalize();
    }

    int Numerator() const {
        return numerator_;
    }

    int Denominator() const {
        return denominator_;
    }

private:
    void Normalize() {
        if (denominator_ < 0) {
            numerator_ = -numerator_;
            denominator_ = -denominator_;
        }
        const int divisor = gcd(numerator_, denominator_);
        numerator_ /= divisor;
        denominator_ /= divisor;
    }

    int numerator_ = 0;
    int denominator_ = 1;
};

ostream& operator<<(ostream& output, Rational MyValue )
{
    output<<MyValue.Numerator()<<"/"<<MyValue.Denominator();
    return output;
}

 istream& operator>>(istream& in, Rational& rat){
    int numerator_, denominator_;
    char slash;
    in >>  numerator_ >> slash >> denominator_;
     rat = Rational{numerator_, denominator_};
        return in;
    }

int main() {
  Rational r10;
    cin >> r10;
   Rational r1();
    Rational r2(8);
    Rational r3(-8);
    Rational r4(1,2);
    Rational r5(-1,2);
    Rational r6(10,-20);
    Rational r7(-1,-2);
    Rational r8(10,15);
    Rational r9(0,-5);

    cout << r10<<endl;
    cout << r7<<endl;
    cout << r8<< endl;
    cout << r9 <<endl;

}