Перегрузка ввода

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <sstream>
#include <cmath>
using namespace std;
class Number
{
private:
    double num;
public:
    Number() { }
    Number(double n) : num(n) { }
    double getNum() const;
    friend istream & operator >> (istream& rt, Number& n1);
    friend istream & operator >> (istream& stream, Number& n2);
    Number operator + (const Number &);
    Number operator - (const Number &);
    Number operator * (const Number &);
    Number operator / (const Number &);
    Number &operator = (const Number &);
};
 
double Number::getNum() const
{
    return num;
}
istream & operator >> (istream& rt, Number& ut)
{
    rt >> ut.num;
    return rt;
}
istream & operator >> (istream& stream, Number& zx)
{
    stream >> zx.num;
    return stream;
}
Number Number::operator + (const Number &rhs)
{
    return Number(num + rhs.getNum());
}
Number Number::operator - (const Number &rhs)
{
    return Number(num - rhs.getNum());
}
Number Number::operator * (const Number &rhs)
{
    return Number(num * rhs.getNum());
}
Number Number::operator / (const Number &rhs)
{
    return Number(num / rhs.getNum());
}
Number &Number::operator = (const Number &rhs)
{
    if (this == &rhs)
        return *this;
    num = rhs.getNum();
    return *this;
}
int main()
{
    Number n1, n2;
    while (1)
    {
        int j;
        cout << "\n";
        cout << "|*************************************|\n";
        cout << "|Enter 0 to the Exit                  |\n"
             << "|*************************************|\n";
        cout << "|Enter 1 to move to division          |\n";
        cout << "|Enter 2 to move to the multiplication|\n";
        cout << "|Enter 3 to move to the alignment     |\n";
        cout << "|Enter 4 to move to the addition of   |\n";
        cout << "|Enter 5 to move to the substraction  |\n"
             << "|*************************************|\n";
        cout << "|You order:                           |\n"; cin >> j;
        cout << "|*************************************|\n";
        if (cin.good())
            switch (j)
        {
            case 0:
                cout << "Program is canceled ";
                system("pause");
                return 0;
            case 1:
                cout << "Enter the first number = "; 
                cin >> n1;
                cout << "\n";
                cout << "Enter the second number = "; 
                cin >> n2;
                cout << "\n";
                cout << "Result = \t"; n1 / n2;
                cout << "\n";
                break;
            case 2:
                cout << "Enter the first number = "; 
                cin >> n1;
                cout << "\n";
                cout << "Enter the second number = "; 
                cin >> n2;
                cout << "\n";
                cout << "Result = "; n1 * n2;
                cout << "\n";
                break;
            case 3:
                cout << "Enter the first number = "; 
                cin >> n1;
                cout << "\n";
                cout << "Enter the second number = "; 
                cin >> n2;
                cout << "\n";
                cout << "Result = "; n1 = n2;
                cout << "\n";
                break;
            case 4:
                cout << "Enter the first number = "; 
                cin >> n1;
                cout << "\n";
                cout << "Enter the second number = ";
                cin >> n2;
                cout << "\n";
                cout << "Result = "; n1 + n2;
                cout << "\n";
                break;
            case 5:
                cout << "Enter the first number = ";
                cin >> n1;
                cout << "\n";
                cout << "Enter the second number = ";
                cin >> n2;
                cout << "\n";
                cout << "Result = "; n1 - n2;
                cout << "\n";
                break;
        }
    }
}