using System;

​

  public class Program

  {

     public static void Main(string[] args)

     {

          double orech;

          double gova;

          double shetach;

          Console.WriteLine("Please enter orech and gova");

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

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

          shetach =(orech * gova)/2;

          Console.WriteLine("The surface is {0}.", shetach);

     }

}

​