using System;

public class Program

{

    public static void Main()

    {

       var name = Console.ReadLine().ToLower();

       if (name == "square")

       {

       var a = double.Parse(Console.ReadLine());

       var area = a * a;

       Console.WriteLine("{0:F3}", area);

       }

       else if (name == "rectangle")

       {

            var a = double.Parse(Console.ReadLine());

            var b = double.Parse(Console.ReadLine());

            var area = a * b;

            Console.WriteLine("{0:F3}", area);

       }

       else if (name == "circle")

       {

           var r = double.Parse(Console.ReadLine());

           var area = r * r * Math.PI;

           Console.WriteLine("{0:F3}", area);

       }

       else if (name == "triangle")

       {

        var a = double.Parse(Console.ReadLine());

        var h = double.Parse(Console.ReadLine());

        var area = (a * h)/2;

        Console.WriteLine("{0:F3}", area);   

      }

   }

}