import java.util.Scanner;

public class AreasOfFigures {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String figure = scanner.nextLine();

        if (figure.equals("square")) {
            double squareSide = Double.parseDouble(scanner.nextLine());
            System.out.printf("%.3f", squareSide * squareSide);
        }else if (figure.equals("rectangle")) {
            double sideA = Double.parseDouble(scanner.nextLine());
            double sideB = Double.parseDouble(scanner.nextLine());
            System.out.printf("%.3f", sideA * sideB);
        }else if (figure.equals("circle")) {
            double length = Double.parseDouble(scanner.nextLine());
            System.out.printf("%.3f", length * length * Math.PI);
        }else if (figure.equals("triangle")) {
            double triangleSide = Double.parseDouble(scanner.nextLine());
            double triangleSideTwo = Double.parseDouble(scanner.nextLine());
            System.out.printf("%.3f", triangleSide * triangleSideTwo / 2);
        }
    }
}