Почему friend ostrem& operator <<(ostream& outs, const Rational&); - invalid function declaration?

#include <iostream>
#include <stdexcept>
#include <cmath>
#include <string>
#include <sstream>
 
 
using namespace std;
 
class Rational
{
public:
    friend Rational operator +(const Rational& num1, const Rational& num2);
    friend Rational operator -(const Rational& num1, const Rational& num2);
    friend Rational operator *(const Rational& num1, const Rational& num2);
    friend Rational operator -(const Rational& num2);
    friend bool operator < (const Rational& num1, const Rational& num2);
    friend bool operator <= (const Rational& num1, const Rational& num2);
    friend bool operator > (const Rational& num1, const Rational& num2);
    friend bool operator >= (const Rational& num1, const Rational& num2);
    friend bool operator == (const Rational& num1, const Rational& num2);
      
   
 
    friend ostrem& operator <<(ostream& outs, const Rational&);
    friend istream& operator >>(istream& ins, Rational&);
    
    Rational(int top_num, int bottom_num);
    Rational( );
 
    double get_value( ) const;
 
    void input(istream& ins);
    void output(ostream& outs) const;
     
private:
    int top_num;
    int bottom_num;
};
 
  
  
int main
{
    
    Rational.test3(int num 1, int num 2);
    Rational test2(int num);
    Rational test1();
    
    cout << "Please enter two non-zero integers: ";
    Rational1.input(cin);
    cout << "Please enter Rational number: ";
    Rational2.input(cin);
    
    
 
// Display the three values to test cout
    Rational test1, test2, test3(2,6);
    cout << "\nTest1 equals " << test1;
    cout << "\nTest2 equals " << test2;
    cout << "\nTest3 equals " << test3;
    
    // Test our operators
    cout << "\nTest1 * Test2 equals " << test1*test2;
    cout << "\nTest1 / Test3 equals " << test1/test3;
    cout << "\nTest2 + Test3 equals " << test2+test3;
    cout << "\nTest3 - Test1 equals " << test3-test1;
    
    
    if (test1 == test2)
        cout << "\nTest1 is equal to Test2";
    if (test1 < test2)
        cout << "\nTest1 is less than Test2";
 
  system("Pause");
  return 0;
} 
       
      Rational operator +(const Rational& num1, const Rational& num2)
      {
       Rational.temp;
       temp.sum = num1.sum + num2.sum;
       return temp;        
      } 
       
       Rational operator -(const Rational& num1, const Rational& num2)
      {
       Rational.temp;
       temp.difer = num1.difer - num2.difer;
       return temp;        
      } 
      
      Rational operator *(const Rational& num1, const Rational& num2)
      {
       Rational.temp;
       temp.multipl = num1.multipl*num2.multipl;
       return temp;        
      }
      
      Rational operator -(const Rational& num2)
      {
       Rational.temp;
       temp.negative = -num.negative;
       return temp;         
      }
   
      bool operator ==(const Rational& num1, const Rational& num2)
      {
        return (num1.equal == num2.equal);     
      }
      
      bool operator < (const Rational& num1, const Rational& num2)
      {
         return (num1.equal < num2.equal);   
      }
            
      bool operator <= (const Rational& num1, const Rational& num2)
      {
        return (num1.equal <= num2.equal);   
      }
      
      bool operator > (const Rational& num1, const Rational& num2)
      {
       return (num1.equal > num2.equal);    
      }
      
      bool operator >= (const Rational& num1, const Rational& num2)
      {
           return (num1.equal >= num2.equal);
       }
       
       
       
       istream& operator >>(istream& ins, const  )
       {
                return ins;
       }
       ostrem& operator <<(ostream& outs, const  )
       {
               return outs;
        }