using System;

using System.Linq;

using System.Security.Cryptography;

using System.Text;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        var n = 3;

​

        string place = "world";

        string greet = String.Format("Hello {0}!", place);

​

        byte[] b1 = System.Text.Encoding.UTF8.GetBytes(greet);

​

        var md5 = MD5.Create();

​

        string strName = md5.GetType().Name;

​

        string HashAlgorithm = new string(strName.Take(n).ToArray());

​

        int previousYear = DateTime.Now.AddYears(-1).Year;

​

        string myString = previousYear.ToString();

​

        string totallyRandomString = new string(myString.Take(n).ToArray());

​

        int myInt = System.Convert.ToInt32(totallyRandomString);

​

        int x = myInt << 1 + 1;

​

        PasswordDeriveBytes DerivedPassword = new PasswordDeriveBytes(place, b1, HashAlgorithm, x);

        byte[] KeyBytes = DerivedPassword.GetBytes(32);

​

        string base64 = Convert.ToBase64String(KeyBytes);

​

        var split = base64.Split('/');

        var last = split[split.Length - 1];

​

        string truncatedToNLength = new string(last.Take(n).ToArray());

​

        Regex rgx = new Regex("[^a-zA-Z0-9 -]");

        greet = rgx.Replace(greet, "");

​

        var newString = greet.Replace(place.ToString(), truncatedToNLength);

​

        var searchStr = newString.ToLower();

​

        Console.WriteLine(searchStr);

    }

}