using System;

​

public class Program

{

    public static void Main()

    {

        string[, ] letters = {{"_","_","_"},{"_","_","_"},{"_","_","_"}};

        while(true){

            for (int i = 0; i < 3; i++)

            {

                for (int j = 0; j < 2; j++)

                {

                    Console.Write(letters[i, j]);

                }

​

                Console.WriteLine();

            }

            Console.WriteLine("First dim: ");

            int num1 = Convert.ToInt32(Console.ReadLine());

            Console.WriteLine("Second dim: ");

            int num2 = Convert.ToInt32(Console.ReadLine());

            letters[num1, num2] = "X";

        }

    }

}