A program to shuffle the lines of a text file

ListShuffler.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>

</Project>

Program.cs

using System;
using System.IO;

using static System.Console;
using static System.IO.File;

namespace ListShuffler
{
    class Program
    {
        static void Main(string[] args)
        {
            
            string fileName;
            if(args.Length < 1)
            {
                WriteLine("Please enter a filename: ");
                fileName = ReadLine();
            }
            else
                fileName = args[0];
            
            
            string[] inputLines, outputLines;
            try
            {
                inputLines = ReadAllLines(fileName);
            }
            catch (Exception x)
            {
                WriteLine(x.ToString());
                return;
            }
            
            int max = inputLines.Length;
            outputLines = new string[max];
            bool[] check = new bool[max];
            // This is for keeping track of lines already included in the new array
            
            Random r = new Random();
            int count = 0, token;

            while(count < max)
            {
                token = r.Next(0, max);
                if(!check[token]) // Means this line has not been used
                {
                    outputLines[count++] = inputLines[token];
                    check[token] = true;
                }
            }
            WriteAllLines(fileName, outputLines);
        }
    }
}

test.txt

7
1
9
3
6
8
5
4
2
0