#include <iostream.h>
class imaginary
{ double x,y;
  public:
	imaginary(double a,double b){x=a;y=b;}
    friend void add(imaginary&A,imaginary&B);
    friend void sub(imaginary&A,imaginary&B);
	friend void mul(imaginary&A,imaginary&B);
	friend void div(imaginary&A,imaginary&B);
	static void show(char c,imaginary&A,imaginary&B);
};
  void add(imaginary&A,imaginary&B)
  { double dx=A.x+B.y;
    double dy=A.y+B.y; 
	cout<<dx<<"+"<<dy<<"i"<<endl;}
  void sub(imaginary&A,imaginary&B)
  { double dx=A.x-B.y;
    double dy=A.y-B.y;
	cout<<dx<<"+"<<dy<<"i"<<endl;}
  void mul(imaginary&A,imaginary&B)
  { double dx=A.x*B.x-A.y*B.y; 
    double dy=A.y*B.x+A.x*B.y;
    cout<<dx<<"+"<<dy<<"i"<<endl;}
  void div(imaginary&A,imaginary&B)
  { double dx=(A.x*B.x+A.y*B.y)/(B.x*B.x+B.y*B.y);
    double dy=(A.y*B.x-A.x*B.y)/(B.x*B.x+B.y*B.y);
    cout<<dx<<"+"<<dy<<"i"<<endl;}

  void imaginary:: show(char c,imaginary&A,imaginary&B)
  {switch(c)
  {   case '+':{add(A,B);break;}
      case '-':{sub(A,B);break;}
	  case '*':{mul(A,B);break;}
	  case '/':{div(A,B);break;}
	  default:cout<<"e!!"<<endl;
	}
  }

		  
void main()
{
	double a,b,d,e;char c;
	cout<<"input the digital "<<endl;
	cin>>a;
    cin>>b;
	cin>>d;
	cin>>e;
    imaginary A(a,b),B(d,e);
    cout<<"input the sign："<<endl;
    cin>>c;
    cout<<"the answer is："<<endl;
    imaginary::show(c,A,B);
}