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

namespace Area_of_Figures
{
    class Program
    {
        static void Main(string[] args)
        {
            string figure = Console.ReadLine();



            if (figure == "square")
            {
                decimal number = decimal.Parse(Console.ReadLine());
                Console.WriteLine(Math.Round(number * number,3));
            }
            else if (figure == "rectangle")
            {
                decimal number = decimal.Parse(Console.ReadLine());
                decimal number2 = decimal.Parse(Console.ReadLine());
                Console.WriteLine(Math.Round(number * number2,3));

            }
            else if (figure == "circle")
            {
                double number = double.Parse(Console.ReadLine());

                Console.WriteLine(Math.Round(Math.PI *number*number,3));

            }
            else if (figure == "triangle")
            {
                decimal number = decimal.Parse(Console.ReadLine());
                decimal number2 = decimal.Parse(Console.ReadLine());
                Console.WriteLine(Math.Round(number * number2,3));
            }
        }
    }
}