public struct Size
{
    public int Length;
    public int Width;
    public int Area()
    {
      return Length*Width;
    }
}

class Program
{
    static void Main(string[] args)
    {
      Size size;
      size.Length = 10;
      size.Width = 5;
      Console.WriteLine(size.Area());
      Console.ReadKey();
    }
}

class Program
{
    static void Main(string[] args)
    {
      Size size;
      size.Length = 10;
      Console.WriteLine(size.Area());
      Console.ReadKey();
    }
}

class Program
{
    static void Main(string[] args)
    {
      Size size = new Size();
      Console.WriteLine(size.Area());
      Console.ReadKey();
    }
}