Print Matrix To Screen (with little pretty box), C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            int[,] matrix = 
            {
                { 1, 2, 3, 4 },
                { 2, 3, 4, 5 },
                { 3, 4, 5, 6 },
                { 7, 8, 9, 0 }
            };
            int columns = matrix.GetLength(0);
            int rows = matrix.GetLength(1);
            for (int i = 0; i < columns; i++){
                if (i == 0){
                    Console.Write("    0 1 2 3\n");
                    Console.WriteLine("  +---------+");
                }
                for (int j = 0; j < rows; j++){
                    if (j == 0) Console.Write(i.ToString() + " | ");
                    Console.Write(matrix[i, j] + " ");
                    if (j == rows-1) Console.Write("|");
                }
                Console.WriteLine();
                if (i == columns-1) Console.Write("  +---------+");
            }
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,14 sec, absolute running time: 0,09 sec, cpu time: 0,08 sec, average memory usage: 12 Mb, average nr of threads: 3