using System;

​

public class MyProgram

{

    private static Random random = new Random();

    public static void Main(String[] args)

    {

        String UN;

        String PW;

        int Try;

        int correct;

        int r1;

        int r2;

        int r3;

        String[] userName = new String[5];

        String[] password = new String[5];

        int count;

        int count2;

        int count3;

        int count4;

        int count5;

        count = 0;

        while (count < 5)

        {

            r1 = random.Next(26) + 65;

            r2 = random.Next(26) + 65;

            r3 = random.Next(26) + 65;

            userName[count] = (char) (r1) + (char) (r2) + (char) (r3);

            count = count + 1;

        }

        count = 0;

        while (count < 5)

        {

            r1 = random.Next(10) + 48;

            r2 = random.Next(10) + 48;

            r3 = random.Next(10) + 48;

            password[count] = (char) (r1) + (char) (r2) + (char) (r3);

            count = count + 1;

        }

        count = 0;

        count2 = 1;

        count3 = 2;

        count4 = 3;

        count5 = 4;

        Console.WriteLine("Enter a username");

        input(out UN);

        Console.WriteLine("Enter Password");

        input(out PW);

        if (UN == userName[count] && PW == password[count])

        {

            Console.WriteLine("Welcome to the system");

        }

        else

        {

            if (UN == userName[count2] && PW == password[count2])

            {

                Console.WriteLine("Welcome to the system");

            }

            else

            {

                if (UN == userName[count3] && PW == password[count3])

                {

                    Console.WriteLine("Welcome to the system");

                }

                else

                {

                    if (UN == userName[count4] && PW == password[count4])

                    {

                        Console.WriteLine("Welcome to the system");

                    }

                    else

                    {

                        if (UN == userName[count5] && PW == password[count5])

                        {

                            Console.WriteLine("Welcome to the system");

                        }

                        else

                        {

                            Try = 1;

                            correct = 0;

                            while (Try < 4 && correct <= 0)

                            {

                                Console.WriteLine("Access Denied");

                                Console.WriteLine("Enter a username");

                                input(out UN);

                                Console.WriteLine("Enter Password");

                                input(out PW);

                                Try = Try + 1;

                                if (UN == userName[count] && PW == password[count])

                                {

                                    correct = 1;

                                }

                                else

                                {

                                    if (UN == userName[count2] && PW == password[count2])

                                    {

                                        correct = 1;

                                    }

                                    else

                                    {

                                        if (UN == userName[count3] && PW == password[count3])

                                        {

                                            correct = 1;

                                        }

                                        else

                                        {

                                            if (UN == userName[count4] && PW == password[count4])

                                            {

                                                correct = 1;

                                            }

                                            else

                                            {

                                                if (UN == userName[count5] && PW == password[count5])

                                                {

                                                    correct = 1;

                                                }

                                            }

                                        }

                                    }

                                }

                            }

                            if (correct == 1)

                            {

                                Console.WriteLine("Welcome to the system");

                            }

                            else

                            {

                                Console.WriteLine("Tries have reached maximum, system shutting down");

                            }

                        }

                    }

                }

            }

        }

    }

    // .NET can only read single characters or entire lines from the console.

    // The following functions are designed to help input specific data types.

    // 'out' is a pass-by-reference modifier in C#.

    private static void input(out double result)

    {

        while (!double.TryParse(Console.ReadLine(), out result));

    }

    private static void input(out int result)

    {

        while (!int.TryParse(Console.ReadLine(), out result));

    }

    private static void input(out Boolean result)

    {

        while (!Boolean.TryParse(Console.ReadLine(), out result));

    }

    private static void input(out string result)

    {

        result = Console.ReadLine();

    }

}

​