using System;
using System.Collections.Generic;

namespace TechModule
{
    class Program
    {
        static double GetTriangleArea(int side, int height)
        {
            double area = height * side / 2;

            return area;
        }

        static double GetSquareArea(int side)
        {
            double area = side * 4;

            return area;
        }

        static double GetRectangleArea(int width, int recHeight)
        {
            double area = width * recHeight;

            return area;
        }

        static double GetCircleArea(double radius)
        {
            double area = Math.PI * Math.Pow(radius, 2);

            return area;
        }

        static void Main()
        {
            string figure = Console.ReadLine();

            double area = 0;

            switch (figure)
            {

                case "triangle":
                    int side = int.Parse(Console.ReadLine());
                    int height = int.Parse(Console.ReadLine());
                    area = GetTriangleArea(side, height);
                    Console.WriteLine("{0:f2}", area);
                    break;

                case "square":
                    int squareSide = int.Parse(Console.ReadLine());
                    area = GetSquareArea(squareSide);
                    Console.WriteLine("{0:f2}", area);
                    break;

                case "rectangle":
                    int width = int.Parse(Console.ReadLine());
                    int recHeight = int.Parse(Console.ReadLine());
                    area = GetRectangleArea(width, recHeight);
                    Console.WriteLine("{0:f2}", area);
                    break;

                case "circle":
                    int radius = int.Parse(Console.ReadLine());
                    area = GetCircleArea(radius);
                    Console.WriteLine("{0:f2}", area);
                    break;

                default:
                    break;
            }
        }
    }
}