import java.util.Scanner;

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

        String figure = scanner.nextLine();

        if (figure.equals("square")){
            double a = Double.parseDouble(scanner.nextLine());
            System.out.printf("%.3f", a*a);
        }
        if (figure.equals("rectangle")) {
            double a = Double.parseDouble(scanner.nextLine());
            double b = Double.parseDouble(scanner.nextLine());
            System.out.printf("%.3f", a * b);
        }
        if (figure.equals("circle")) {
            double r = Double.parseDouble(scanner.nextLine());
            System.out.printf("%.3f", r*r * Math.PI);
        }
        if (figure.equals("triangle")) {
            double a = Double.parseDouble(scanner.nextLine());
            double h = Double.parseDouble(scanner.nextLine());
            System.out.printf("%.3f", (a*h)/2);
        }
    }
}