import java.util.Scanner;

public class Solution {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String shapeType = sc.next();
        double area=0.0;
        
        if(shapeType.equalsIgnoreCase("circle")) {
            double radius = sc.nextDouble();
                if(radius<0) {
                    System.out.println("Invalid input");
                    return;
                }
                area = calculateArea(radius);
        }
        else if (shapeType.equalsIgnoreCase("square")) {
            double length = sc.nextDouble();
                double width = sc.nextDouble();
                if(length<0 || width<0) {
                    System.out.println("Invalid input");
                    return;
                }
                area = calculateArea(length, width);
        }
        else if (shapeType.equalsIgnoreCase("square")) {
            float side = sc.nextFlot();
                if(side<0) {
                    System.out.println("Invalid input");
                    return;
                }
                area = calculateArea(side);
        }
        else {
            System.out.println("Invalid input");
            return;
        }
        
        System.out.printf("%.2f", area);
    }
    
    static double calculateArea(double a) {
        return Math.PI * a * a;
    }
    
    static double calculateArea(double a, double b) {
        return a * b;
    }
    
    static double calculateArea(float a) {
        return (double)a * a;
    }
}