How to access elements in a rectangular array in C#?

a[0,1]; // second element

using System;

namespace Demo {

   class Program {
      static void Main(string[] args) {

         int[,] a = new int[3, 3];
         a[0,0]= 10;
         a[0,1]= 20;
         a[0,2]= 30;
         a[1,0]= 40;
         a[1,1]= 50;
         a[1,2]= 60;
         a[2,0]= 70;
         a[2,1]= 80;

         // accessing element
         a[2,2]= 90;

         int i, j;
   
         for (i = 0; i < 3; i++) {
            for (j = 0; j < 3; j++) {
               Console.WriteLine("a[{0},{1}] = {2}", i, j, a[i,j]);
            }
         }

         int ele = a[0,1];
         Console.WriteLine("Second element: "+ele);

         Console.ReadKey();
      }
   }
}