Area

import java.util.Scanner;

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

        String shape = scan.nextLine();

        double side, height = 0;

        side = Double.parseDouble(scan.nextLine());

        if(shape.equals("rectangle") || shape.equals("triangle")){
            height = Double.parseDouble(scan.nextLine());
        }

        double area = 0;

        if (shape.equals("square")){
            area = side * side;
        }
        else if(shape.equals("circle")){
            area = Math.PI * Math.pow(side, 2);
        }
        else if(shape.equals("rectangle")){
            area = side * height;
        }
        else{
            area = side * height / 2;
        }

        System.out.println(area);
    }
}