import java.util.Scanner;

public class AreaFigures {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
       String type = scanner.nextLine();
        double area =0.0;
        if (type.equals("square")){
            double a = Double.parseDouble(scanner.nextLine());
            area = a * a;
        }else if (type.equals("rectangle")) {
            double a = Double.parseDouble(scanner.nextLine());
            double b = Double.parseDouble(scanner.nextLine());
            area = a * b;
        }else if (type.equals("circle")){
            double r = Double.parseDouble(scanner.nextLine());
            area = Math.PI*r*r;
        }else if (type.equals("triangle"));{
            double a = Double.parseDouble(scanner.nextLine());
            double h = Double.parseDouble(scanner.nextLine());
            area = a*h/2;
        }
        System.out.printf("%.3f", area);
    }
}