#include <stdio.h>

struct complex{
    int real;
    int imag;
};

struct complex multiply(struct complex x, struct complex y);

int main()
{
    struct complex product, x, y;

    scanf("%d%d%d%d", &x.real, &x.imag, &y.real, &y.imag);
    product = multiply(x, y);
    printf("(%d+%di) * (%d+%di) = %d + %di\n", 
            x.real, x.imag, y.real, y.imag, product.real, product.imag);

    return 0;
}

struct complex multiply(struct complex x, struct complex y){
	struct complex s;
	s.real=x.real*y.real-x.imag*y.imag;
	s.imag=x.real*y.imag+x.imag*y.real;
	return s;
	//这和调用函数很类似，只不过类型由最简单的int转变为结构体struct complex
	//而multiply是这个函数的名字，用来承载结果的时候需要定义一个新的struct complex型的变量
	//自己糊里糊涂犯错误直接用函数名计算了，导致编译错误 
}
//也就是每出现此结构体类型的，就代表该变量具有结构体中的所有属性！！！