import java.io.*;

/**
 * re-use Java libraries.
 * For more accurate results, use Math.PI
 */

public class Circle3 {
  //public static final double PI = 3.14;

  public static void main(String argv[]) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    System.out.print("Please enter the radius of the circle: ");
    String input = br.readLine();
    double radius = Double.parseDouble(input);
    double area = Math.PI * radius * radius;
    System.out.println("The area of a circle with radious " + radius + " is: " + area);
  }
}