AreaOfFigures

using System;


class AreaOfFigures
{
    static void Main()
    {
        string figure = Console.ReadLine();
        double firstNum = double.Parse(Console.ReadLine());
        double secondNum = double.Parse(Console.ReadLine());
        double result;
        if (figure == "square")
        {
            result = firstNum * firstNum;
            Console.WriteLine("{0:f3}", result);
        }
        else if (figure == "circle")
        {
            result = Math.PI * (firstNum * firstNum);
            Console.WriteLine("{0:f3}", result);
        }
        else if (figure == "rectangle")
        {
            result = firstNum * secondNum;
            Console.WriteLine("{0:f3}", result);
        }
        else if (figure == "triangle")
        {
            result = (firstNum * secondNum) / 2;
            Console.WriteLine("{0:f3}", result);
        }
    }
}