Перегрузка операторов

#include <iostream>
#include <conio.h>
#include <Windows.h>
 
class Distance {
private:
    int cm;
    int m;
 
public:
    Distance(int cm = 0, int m = 0) {
        this->cm = cm;
        this->m = m;
    }
 
    void getDist() {
 
        std::cout << "Enter cantimeters: ";
        while (!(std::cin >> cm) || (std::cin.peek() != '\n')) {
            std::cin.clear();
            std::cin.ignore(99999, '\n');
            std::cout << "Enter cantimeters: ";
        }
 
        std::cout << "Enter meters: ";
        while (!(std::cin >> m) || (std::cin.peek() != '\n')) {
            std::cin.clear();
            std::cin.ignore(99999, '\n');
            std::cout << "Enter meters: ";
        }
 
    }
 
    void showDist(int mode = -1) const {
        if (mode == -1) {
            std::cout << "Cantimeters: " << cm << "\n";
            std::cout << "Meters: " << m << "\n";
        } else if (mode == 0) {
            float totalCm = cm + (m * 100);
            float result = totalCm/100;
            std::cout << "Meters: " << result << "\n";
        } else if (mode == 1){
            int totalCm = cm + (m * 100);
            std::cout << "Cantimeters: " << totalCm << "\n";
        } else if (mode == 2) {
            float totalCm = cm + (m * 100);
            float result = totalCm/100000;
            std::cout << "Kilometers: " << result << "\n";
        } else {
            std::cout << "Cantimeters: " << cm << "\n";
            std::cout << "Meters: " << m << "\n";
        }
        std::cout << "\n";
    }
 
    Distance& add(const Distance& other) {
        this->m += other.m;
        this->cm += other.cm;
        return *this;
    }
    Distance& subtract(const Distance& other) {
        this->m -= other.m;
        this->cm -= other.cm;
        return *this;
    }
    Distance& multiply(const Distance& other) {
        this->m *= other.m;
        this->cm *= other.cm;
        return *this;
    }
    Distance& divide(const Distance& other) {
        this->m /= other.m;
        this->cm /= other.cm;
        return *this;
    }
 
    friend Distance& operator+(Distance left, const Distance& right) { return left.add(right); }
    friend Distance& operator-(Distance left, const Distance& right) { return left.subtract(right); }
    friend Distance& operator*(Distance left, const Distance& right) { return left.multiply(right); }
    friend Distance& operator/(Distance left, const Distance& right) { return left.divide(right); }
 
    Distance& operator+=(const Distance& other) { return this->add(other); }
    Distance& operator-=(const Distance& other) { return this->subtract(other); }
    Distance& operator*=(const Distance& other) { return this->multiply(other); }
    Distance& operator/=(const Distance& other) { return this->divide(other); }
 
};
 
int main() {
 
    Distance d1;
    d1.getDist();
    Distance d2(160, 3);
    Distance d3;
    d3 += d1 - d2;
    system("cls");
 
    std::cout << "d1:\n";
    d1.showDist(1);
    std::cout << "d2:\n";
    d2.showDist(1);
    std::cout << "d3:\n";
    d3.showDist(1);
 
    _getch();
    return 0;
}

    Distance operator+(const Distance& right) const
    {
        return Distance(*this).add(right);
    }
    Distance operator-(const Distance& right) const
    {
        return Distance(*this).subtract(right);
    }
    Distance operator*(const Distance& right) const
    {
        return Distance(*this).multiply(right);
    }
    Distance operator/(const Distance& right) const
    {
        return Distance(*this).divide(right);
    }