using System;

public class Program
{
    public static void Main()
    {
        string figuretype = Console.ReadLine();
        double area = 0.0;


        switch (figuretype)
        {
            case "square":
        {
            double a = double.Parse(Console.ReadLine());
            area = a*a;
              break;
        }
        case "rectangle":
        {
            double a = double.Parse(Console.ReadLine());
            double b = double.Parse(Console.ReadLine());
                area = a*b;
              break;
        }

                case "circle":
                {
                double radius = int.Parse(Console.ReadLine());
                area = Math.PI * radius * radius;
                break;
                }

        case "triangle":
        {
            double side = double.Parse(Console.ReadLine());
            double hight = double.Parse(Console.ReadLine());
            area = side * hight / 2 ;
              break;
        }
    }
        Console.WriteLine($"{area:F3}");
}
}