public class Main {
public static void main(String[] args) {
System.out.print("Radius: ");
try(java.util.Scanner s = new java.util.Scanner(System.in)) {
double r = s.nextInt();
if (r >= 0) {
System.out.println("Area: " + Math.PI*r*r);
} else {
System.out.println("Radius must be greater than 0.");
}
} catch(Exception e) {
System.out.println("Invalid input");
}
}
}