package threepoint;
import point.Point;

class ThreePoints extends Point {
    protected int z;        
  
    // following produces compile error  
//    public void delta(Point p) {
//       p.x += this.x;              
//       p.y += this.y;
//    }
    
    public void delta(ThreePoints p) {
       p.x += this.x;        
       p.y += this.y;          
   }
}