#include <iostream.h>class Complex{public:?Complex(){real=0;imag=0;}?Complex(double r){real=r;imag=0;}?Complex(double r,double i){real=r;imag=i;}?friend Complex operator+ (Complex &c1,Complex &c2);?_____________private:?_____________?double imag;};Complex operator+ (Complex &c1,Complex &c2){return Complex(c1.real+c2.real, c1.imag+c2.imag);}void Complex::display(){cout<<"("<<real<<","<<imag<<"i)"<<endl;}int main(){?int a,b,c,d;?cin>>a>>b>>c>>d;?Complex c1(a,b),c2(c,d),c3;?c3=c1+c2;?cout<<"c1="; c1.display();?cout<<"c2="; c2.display();?cout<<"c1+c2="; c3.display();?return 0;}