using System;

public class Program

{

    public static void Main()

    {

        string figure = Console.ReadLine().ToLower();

        double result = 0;

        if(figure == "square")

        {

            double num = double.Parse(Console.ReadLine());

            result = num * num;

        }

        else if(figure == "triangle")

        {

            double n1 = double.Parse(Console.ReadLine());

            double n2 = double.Parse(Console.ReadLine());

            result = (n1 * n2) /2;

        }

        Console.WriteLine(result);

    }

}