📅  最后修改于: 2022-03-11 14:52:16.964000             🧑  作者: Mango
import java.util.Scanner;
public class Main {
public static void main(String[] args){
double R,A;
Scanner sc = new Scanner(System.in);
R = sc.nextDouble();
A = 3.14159 * R * R;
System.out.printf("A=%.4f\n", A);
}
}