using System;

public class Program

{

    public static void Main()

    {

        string ValidUserName = "user";

        string ValidPassword = "pass";

        string UserName = "";

        string UserPassword = "";

        bool ValidUserNameFlag = false;

        bool ValidUserPasswordFlag = false;

        bool ValidCredentials = false;

        string[] ValidUserNames = new string[] {"user", "Bob", "Jane"};

        string[] ValidUserPasssword = new string[] {"pass", "1234", "!@#$"};

        do

        {

        Console.WriteLine("User Name or Email");

        UserName = Console.ReadLine();

        Console.WriteLine("Password");

        UserPassword = Console.ReadLine();

        int userToCheck = 0;

        do

        if(UserName == ValidUserName)

        {

          ValidUserNameFlag = true;

        }

        if(UserPassword == ValidPassword)

        {

            ValidUserPasswordFlag = true;

        }

        if(ValidUserNameFlag == true && ValidUserPasswordFlag == true );

        {

            ValidCredentials = true;

            break;

        }

        userToCheck++;

            Console.WriteLine("Invalid Credentials");

            {

        }while(userToCheck < ValidUserName.Length);

        if(ValidCredentials == false)

        {   

        Console.WriteLine("Invalid Credentials");

        }

    }while(ValidCredentials);

    Console.WriteLine("Welcome Back");

​

    }

}