C++ :

#include <iostream>
using namespace std;
class Complex

{ int real,imag;
public:
   	Complex( ):real(0),imag(0){}
	Complex(int r,int i):real(r),imag(i){}
	friend Complex operator *(Complex& c1,Complex& c2);
	friend istream & operator>>(istream & input,Complex& c);
	friend ostream & operator<<(ostream & out,Complex& c);
};

istream & operator>>(istream &input,Complex& c)
{input>>c.real>>c.imag;
return input;}

ostream & operator<<(ostream & out,Complex& c)
{   
	out<<c.real;
		if (c.imag>0) out<<"+";
		if (c.imag!=0) out<<c.imag<<"i"<<endl;
return out;}

Complex operator *(Complex& c1,Complex& c2)
{Complex c;
c.real=c1.real*c2.real-c1.imag*c2.imag;
c.imag=c1.imag*c2.real+c1.real*c2.imag;
return c;
}

int main()
{Complex c1,c2,c3;
	cin>>c1>>c2;
	c3=c1*c2;
    cout<<c3;
 
	return 0;}