using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var figure = Console.ReadLine();
            var pi = 3.14159265359;

            switch (figure)
            {
                case "square":
                    double square = double.Parse(Console.ReadLine());

                    Console.WriteLine($"{square * square:F3}");
                    break;
                case "rectangle":
                    double rectangle1 = double.Parse(Console.ReadLine());
                    double rectangle2 = double.Parse(Console.ReadLine());

                    Console.WriteLine($"{rectangle1 * rectangle2:F3}");
                    break;
                case "circle":
                    double circle = double.Parse(Console.ReadLine());

                    Console.WriteLine($"{pi*(circle*circle):F3}");
                    break;
                case "triangle":
                    double triagle1 = double.Parse(Console.ReadLine());
                    double triagle2 = double.Parse(Console.ReadLine());

                    Console.WriteLine($"{triagle1 * (triagle2/2):F3}");
                    break;
                default:
                    break;
            }
        }
    }
}