//เขียนโปรแกรมโดย ชินดนัย  กรไชยา

using System;

public class Program

{

    public static void Main()

    {

        double h = 0.5;

        double l,g;

        Console.Write("Enter l ; ");

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

        Console.Write("Enter g ; ");

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

        double area = h * g * l; 

        Console.WriteLine("Triangle area = {0}",area);

    }

}