s

using System;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            string name = Console.ReadLine();
            double allSide = 0;
            if (name == "square")
            {
                double side1 = double.Parse(Console.ReadLine());
                allSide = side1 * side1;
            }
             if (name == "rectangle")
            {
                double side1 = double.Parse(Console.ReadLine());
                double side2 = double.Parse(Console.ReadLine());
                 allSide = side1 * side2;
            }
             if (name == "circle")
            {
                double side1 = double.Parse(Console.ReadLine());
                allSide = (side1 * side1 *Math.PI) ;
            }
             if (name == "triangle")
            {
                double side1 = double.Parse(Console.ReadLine());
                double side2 = double.Parse(Console.ReadLine());
                 allSide = side1 * side2/2;
            }
            Console.WriteLine($"{allSide:f3}");
        }
    }
}