#include<stdio.h>
double result_real, result_imag;
void complex_prod( double x1, double y1, double x2, double y2 );
int main(void)
{
double imag1, imag2, real1, real2;
scanf("%lf %lf", &real1, &imag1);
scanf("%lf %lf", &real2, &imag2);
complex_prod(real1, imag1, real2, imag2);
printf("product of complex is (%f)+(%f)i\n", result_real, result_imag);
return 0;
}
void complex_prod( double x1, double y1, double x2, double y2 )
{
result_real = ( x1*x2 - y1*y2 );
result_imag = ( x1*y2 + x2*y1 );
}