using System;

namespace Area_of_Figures
{
    class Program
    {
        static void Main(string[] args)
        {
            string figures = Console.ReadLine();
            double side1 = double.Parse(Console.ReadLine());
            double side2 = double.Parse(Console.ReadLine());

            double areaSquare = side1 * side1;
            double areaRectange = side1 * side2;
            double areaCircle = Math.PI * (side1 * side1);
            double areaTriangle = (side1 * side2) / 2;

            if (figures == "square")
            {
                Console.WriteLine($"{areaSquare:F3}");
            }
            else if (figures == "rectangle")
            {
                Console.WriteLine($"{areaRectange:F3}");
            }
            else if (figures == "circle")
            {
                Console.WriteLine($"{areaCircle:F3}");
            }
            else if (figures == "triangle")
            {
                Console.WriteLine($"{areaTriangle:F3}");
            }
        }
    }
}