using System;

namespace ConsoleApp1
{
    internal class Program
    {
        public static void Main(string[] args)
        {
            int[,] numbersArray =
            {
                { 1, 2, 3 },
                { 4, 5, 6 },
                { 7, 8, 9 },
            };

            for (int i = 0; i < numbersArray.GetLength(0); i++)         
            {
                for (int j = 0; j < numbersArray.GetLength(1); j++)
                {
                    if (i == j) 
                    {
                        Console.Write(numbersArray[i,j]+" ");
                    }
                }
            }
        }
    }
}