#include <stdio.h>

struct point {
  int x, y;
};

struct rectangle {
  struct {
    int x, y;
  }  p1, p2;
};

int main(void) {
  struct rectangle r;
  struct point pt1, pt2;

  /* OK - initialization of x,y coordinates of points in rectangles */
  r.p1.x = 1;   r.p1.y = 2;
  r.p2.x = 10;  r.p2.y = 12;

  /* Not OK - cannot assign points to the fields of rectangle */
  pt1.x = 1;  pt1.y = 2;
  pt2.x = 10; pt2.y = 12;
  r.p1 = pt1;  /* error: incompatible types */
  r.p2 = pt2;  /* error: incompatible types */

  return 0;
}