namespace exerciseSecondL{
    class exerciseSecondL{
      static void Main(){
            double a = double.Parse(System.Console.ReadLine());
            double h = double.Parse(System.Console.ReadLine());
            double areaTriangle = a*h/2;

            System.Console.WriteLine($"Triangle area = {System.Math.Round(areaTriangle,2)}");
      }
	}
}