Foreach Loop with Multi Dimensional Array in C#

using System.IO;
using System;
class foreachLoopMultiDimensionalArray
{
   private static void Main(string[] args)
   {
      int [,] rollnumbers = new [,] { {100, 200}, {300, 400}};
      foreach(int rollnumber in rollnumbers)
      {
         Console.WriteLine("Roll Number: {0}", rollnumber);
      }
   }
}