using System;

​

public class Program

{

    static bool isValidEntryComplete;

    public static void Main()

    {

        while (!isValidEntryComplete)

        {

            ValidateNewClientPromo();

        }

    }

​

    static void ValidateNewClientPromo()

    {

        Console.WriteLine("Hello, are you a new or existing client?");

        Console.WriteLine("Please enter the term " + "new " + "or existing and hit enter");

        var result = Console.ReadLine().ToLowerInvariant();

        bool isNewClient;

        if (IsValidClient(result, out isNewClient))

        {

            if (isNewClient)

            {

                Console.WriteLine("Welcome new client, here is your link: " + "www.google.com");

                isValidEntryComplete = true;

                return;

            }

            else

            {

                Console.WriteLine("Sorry but the promo is only valid for new clients.");

                isValidEntryComplete = true;

                return;

            }

        }

​

        Console.WriteLine("The input: " + result + "is invalid, sorry please try again");

        isValidEntryComplete = false;

    }

​

    private static bool IsValidClient(string input, out bool isNew)

    {

        var is_new = input.Contains("new");

        isNew = is_new;

        if (is_new)

        {

            return true;

        }

        else if (input.Contains("existing"))

        {

            isNew = false;

            return true;

        }

​

        return false;

    }

}