Add Complex Numbers

#include <iostream>     
using namespace std;    
class complex_number  {     
public :        
int real, imag;  
};    
int main()  {     
complex_number num1, num2, sum;       
//getting the value of first complex number from user     
cout << "Enter real and imaginary parts of first complex number:"<<endl;      
cin >> num1.real >> num1.imag;       
//getting the value of second complex number from user     
cout << "Enter real and imaginary parts of second complex number:"<<endl;      
cin >> num2.real >> num2.imag;       
//addition of real and imaginary parts of complex numbers entered by user     
sum.real = num1.real + num2.real;     
sum.imag = num1.imag + num2.imag;       
//displaying the sum of complex numbers     
if ( sum.imag >= 0 )       
cout << "Sum of two complex numbers = " << sum.real << " + " << sum.imag << "i";     
else        
cout << "Sum of two complex numbers = " << sum.real << " - " << sum.imag << "i";       
return 0;  }

Enter real and imaginary parts of first complex number:  
4 6  
Enter real and imaginary parts of second complex number:  
2 3  
Sum of two complex numbers = 6 + 9i