using System;

    class Program
    {
        static void Main()
        {
            string figura = Console.ReadLine();
            if (figura == "square")
            {
                double a = double.Parse(Console.ReadLine());
                double area = a * a;
                Console.WriteLine("{0:F3}", area);
            }
            else if (figura == "rectangle")
            {
                double a = double.Parse(Console.ReadLine());
                double b = double.Parse(Console.ReadLine());
                double area = a * b;
                Console.WriteLine("{0:F3}", area);
            }
            if (figura == "circle")
            {
                double r = double.Parse(Console.ReadLine());
                double area = Math.PI * r * r;
                Console.WriteLine("{0:F3}", area);
            }
            else if (figura == "triangle")
            {
                double a = double.Parse(Console.ReadLine());
                double h = double.Parse(Console.ReadLine());
                double area = a * h / 2;
                Console.WriteLine("{0:F3}", area);
            }
        }
    }