View difference between Paste ID: DvrSbZQ6 and t7FvJQRE

 #include <iostream>
 #include <numeric>
 
 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_;
         }
         int n = gcd(numerator_, denominator_);
         numerator_ /= n;
         denominator_ /= n;
     }
 
     int numerator_ = 0;
     int denominator_ = 1;
 };
 
 ostream& operator<<(ostream& output, Rational rational) {
     output << rational.Numerator() << '/' << rational.Denominator();
     return output;
 }
 
 istream& operator>>(istream& input, Rational& rational) {
     int numerator, denominator;
     char slash;
     input >> numerator >> slash >> denominator;
     rational = Rational{numerator, denominator};
     return input;
 }
 
 Rational operator+(Rational r) {
     return r;
 }
 
 
 Rational operator-(Rational r) {
     return {-r.Numerator(), r.Denominator()};
 }
 
 Rational operator+(Rational left, Rational right) {
     const int numerator = left.Numerator() * right.Denominator()
                   + right.Numerator() * left.Denominator();
     const int denominator = left.Denominator() * right.Denominator();
 
     return {numerator, denominator};
 }
 
 Rational operator-(Rational left, Rational right) {
     const int numerator = left.Numerator() * right.Denominator()
                   - right.Numerator() * left.Denominator();
     const int denominator = left.Denominator() * right.Denominator();
 
     return {numerator, denominator};
 }