#include <stdio.h>

typedef struct {
    int x;
    int y;
} point;

point addpoints(point pt1, point pt2)
{
   pt1.x += pt2.x;
   pt1.y += pt2.y;
   return pt1;
}

int main(void)
{
    point pt1 = {100, 200};
    point pt2 = { 10,  20};
    point pt3 = {  0,   0};

    printf("(%d, %d) (%d, %d) (%d, %d)\n", pt1.x, pt1.y,
                                           pt2.x, pt2.y,
                                           pt3.x, pt3.y);

    pt3 = addpoints(pt1, pt2);

    printf("(%d, %d) (%d, %d) (%d, %d)\n", pt1.x, pt1.y,
                                           pt2.x, pt2.y,
                                           pt3.x, pt3.y);

    return 0;
}