using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        string  tx = string.Format("{0} {1}", null, null);

        Console.WriteLine(tx);

        string userfirstname = "mohammed";

        string userlastname = "rizwan";

        string userfullname = string.Concat(userfirstname, userlastname);

        string password = "rizwan";

         if (IsPasswordValid(password,userfullname)){

             Console.WriteLine("good to go");

         }

        else{

             Console.WriteLine("Should not contain 3 consec characters");

        }

    }

    public static bool IsPasswordValid(string newPassword, string userfullName)

  {

       //Create a collection of all of the 3-character substrings

       List<string> substrings = new List<string>();

       for (int i = 0; i < userfullName.Length-2; i++)

       {

            //Adds the 3-character substring

            substrings.Add(userfullName.Substring(i, 3));

       }

​

       //Checks if the new password contains any of the 3-character subsets

       return !substrings.Any(s => newPassword.Contains(s));

}

}