Area

using System;

namespace AreaFigura
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] data = {"square", "rectangle", "circle","triangle" };
            string type = Console.ReadLine();
            double bank = 0.0;
            if (type==data[0])
            {
                double a = double.Parse(Console.ReadLine());
                bank = a * a;

            }
            else if (type == data[1])
            {
                double a = double.Parse(Console.ReadLine());
                double b = double.Parse(Console.ReadLine());
                bank = a * b;
            }
            else if (type == data[2])
            {
                double radius = double.Parse(Console.ReadLine());
                bank = Math.PI * Math.Pow(radius,2);
            }
            else if (type == data[3])
            {
                double a = double.Parse(Console.ReadLine());
                double b = double.Parse(Console.ReadLine());
                bank = a * b/2;
            }
            Console.WriteLine(Math.Round(bank,3));
        }
    }
}