Area

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Area
{
    class Program
    {
        static void Main(string[] args)
        {
            var figure = Console.ReadLine().ToLower();
            var a = double.Parse(Console.ReadLine());

            if(figure == "square")
            {

                Console.WriteLine(Math.Round(a * a , 3));
            }
            else if(figure == "circle")
            {

                Console.WriteLine(Math.Round(a * a * Math.PI , 3));
            }
            else
            {
                var b = double.Parse(Console.ReadLine());

                if(figure == "triangle")
                {

                    Console.WriteLine(Math.Round(a * b / 2 , 3));
                }
                if(figure == "rectangle")
                {

                    Console.WriteLine(Math.Round(a * b , 3));
                }
            }

        }
    }
}