public class Circle {
  public double radius;

  public double getArea() {
   return Math.PI*radius*radius;
  }

  public double getCircumference() {
   return 2.0*Math.PI*radius;
  }

  public double getDiameter() {
   return 2.0*radius;
  }

  public double getRadius() {
   return radius;
  }
}