using System;

​

public class Program

{

    public static void Main()

    {

        string ValidNames = "user";

        string ValidUserPassword = "pass";

        string UserName = "";

        string UserPassword = "";

        bool ValidUserNameFlag = false;

        bool ValidUserPasswordFlag = false;

        bool ValidCredentials = false ;

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

        string[] ValidUserPasswords = new string[] {"pas","1234","!@#$"};

        int eachUser = 0;

        do

        {

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

        UserName = Console.ReadLine();

        Console.WriteLine("Password");

        UserPassword = Console.ReadLine();

        if(UserName == ValidUserNames[ eachUser] )

        { //set valid username

            ValidUserNameFlag = true;

        }

​

        if (UserPassword == ValidUserPasswords [eachUser])

        {

            ValidUserPasswordFlag = true;

        }

​

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

        {

         ValidCredentials= true ;   

            break; 

        }

​

            eachUser++;

            } while (eachUser < ValidUserNames .Length);

        if (ValidCredentials  == false)

        {

        Console.WriteLine("Invalid Credentials");

        }

        else

        {

        }while(! ValidCredentials); 

        Console.WriteLine("Welcome back");

    }

}