import java.util.Scanner;

public class anotherExercise {
    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());
            double area =a*a;
        }else if (type.equals("rectangle")){
            double a=Double.parseDouble(scanner.nextLine());
            double b=Double.parseDouble(scanner.nextLine());
            double area=a*b;
        }else if (type.equals("circle")){
            double a=Double.parseDouble(scanner.nextLine());
            double area= Math.PI*a*a;
        }else if (type.equals("triangle")){
            double a=Double.parseDouble(scanner.nextLine());
            double b=Double.parseDouble(scanner.nextLine());
            double area=a*b/2;
        }
        System.out.printf("%.3f",area);
    }
}