areaOfFigures

import java.util.Scanner;

public class Nums100 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String figType = scanner.nextLine();

        double area = 0;
        switch (figType) {
            case "square": {
                double a = Double.parseDouble(scanner.nextLine());
                area = a * a;
                break;
            }
            case "rectangle": {
                double a = Double.parseDouble(scanner.nextLine());
                double b = Double.parseDouble(scanner.nextLine());
                area = a * b;
                break;
            }
            case "circle": {
                double r = Double.parseDouble(scanner.nextLine());
                area = Math.PI * r * r;
                break;
            }
            case "triangle": {
                double side = Double.parseDouble(scanner.nextLine());
                double height = Double.parseDouble(scanner.nextLine());
                area = (side * height)/2;
                break;


            }



        }
        System.out.printf("%.3f", area);
        }
    }