class Circle {

 num x;
 num y;
 num radius;

 Circle(this.x, this.y, this.radius);

 Circle clone() => new Circle(x, y, radius);

 String toString() => "Circle [x=$x, y=$y, radius=$radius]";

 //-----------------------------------------------------------------------------------------------
 //-----------------------------------------------------------------------------------------------

 bool contains(num x, num y) {
   var dx = this.x - x;
   var dy = this.y - y;
   return dx * dx + dy * dy < radius * radius;
 }

 bool containsPoint(Point p) {
   var dx = this.x - p.x;
   var dy = this.y - p.y;
   return dx * dx + dy * dy < radius * radius;
 }
}