SoftUni party

using System;
using System.Collections.Generic;

namespace SoftUni_Party
{
    class Program
    {
        static void Main(string[] args)
        {
            string input = Console.ReadLine();
            HashSet<string> VIPguests = new HashSet<string>();
            HashSet<string> REGULARguests = new HashSet<string>();
            int count = 0;

            while (input!="PARTY")
            {
                string reservation = input;

                if (char.IsDigit(reservation[0]))
                {
                    VIPguests.Add(reservation);
                }

                else
                {
                    REGULARguests.Add(reservation);
                }

                count++;
                input = Console.ReadLine();
            }

            string newInput = Console.ReadLine();

            while (newInput != "END")
            {
                string guest = newInput;

                if (VIPguests.Contains(guest))
                {
                    VIPguests.Remove(guest);
                    count--;
                }

                else if (REGULARguests.Contains(guest))
                {
                    REGULARguests.Remove(guest);
                    count--;
                }

                newInput = Console.ReadLine();
            }

            Console.WriteLine(count);

            foreach (var guest in VIPguests)
            {
                Console.WriteLine(guest);
            }

            foreach (var guest in REGULARguests)
            {
                Console.WriteLine(guest);
            }

        }
    }
}