import java.util.Scanner;
public class S{
public static void main(String[] args){
Scanner input=new Scanner("System.in");
System.out.print("请输入圆的半径：");
double r=input.nextDouble();
final float PI=3.14f;
double S=PI*r*r;
System.out.println("圆的面积为："+S);
}
}
public class S{
public static void main(String[] args){
Scanner input=new Scanner("System.in");
System.out.print("请输入圆的半径：");
double r=input.nextDouble();
final float PI=3.14f;
double S=PI*r*r;
System.out.println("圆的面积为："+S);
}
}
