#include
     
      using namespace std;class rectangle {public: double area(double l,double w);private:double length,width;};double rectangle::area(double l,double w){length=l;width=w;return length*width;}int main(){rectangle Rectangle; double length,width;cin>>length>>width;cout<
      
       <
      
     

#include
     
      using namespace std;class Complex{    public:    Complex(double r0,double i0){        real=r0;        imaginary=i0;            };    Complex(Complex &c0);    void add(Complex &C0)    void show();    private:        double real,imaginary;        };void Complex::add(Complex &c0){    real+=c0.real,imaginary+=c0.imaginary;    }void Complex::show(){    cout<
      
       <
       
        <<'i'<