boomOrBloom

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace BoomsOrBlooms
{
    class Program
    {
        static void Main(string[] args)
        {

            while (true)
            {
                Console.WriteLine("enter either boom or bloom");
                string input = Console.ReadLine().ToLower();
                if (input != "boom" && input != "bloom") continue;
                Countdown(5);
                string reponse = null;
                if (reponse == "boom") Flashscreen(ConsoleColor.Red, ConsoleColor.Yellow);
                else Flashscreen(ConsoleColor.Green, ConsoleColor.Blue);
            }
        }
        static void Flashscreen(ConsoleColor color1, ConsoleColor color2)
        {
            for (int i=0; i < 10; ++i)
            {
                Console.BackgroundColor = color1;
                Console.Clear();
                Thread.Sleep(500);
                Console.BackgroundColor = color2;
                Console.Clear();
                Thread.Sleep(500);
            }
            Console.ResetColor();
            Console.Clear();
        }
        static void Countdown(int nSeconds)
        {
            while(nSeconds > 0)
            {
                Console.WriteLine(nSeconds--);
                Thread.Sleep(1000);
            }
        }
    }
}