class Area{
static double area(double r){
	 return Math.PI*r*r;
}
static double area(double l,double w){
	 return l*w;
}
public static void main(String args[]){
	   double circle;
	    circle=area(10);
	    System.out.println("半徑為10的圓面積是:"+circle);
	    double rectangle;
	    rectangle=area(10,20);
	    System.out.println("長為10寬為20的矩形面積是:"+rectangle);
}
}