using System;

public class Program

{

    public static void Main()

    {

​

             double panelArea = 1.425;

            int roofWidth = Convert.ToInt32(Console.ReadLine());

            int roofDepth = Convert.ToInt32(Console.ReadLine());

            int roofArea = roofWidth * roofDepth;

            double numPanels = (roofArea / panelArea) -(roofArea % panelArea);

            Console.WriteLine(numPanels);

    }

}