Игра в слова

using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Linq;
using System.Net.NetworkInformation;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.IO;
 
public class Program
{
    static Random rnd = new Random();
    public static void Main()
    {
        var allWords = File.ReadAllLines(@"c:\c#\word_rus.txt");
        var word = allWords[rnd.Next(allWords.Length)];
        var letters = word.GroupBy(c => c).ToDictionary(c => c.Key, c => c.Count());
        Console.WriteLine(word);
        var userWord = "";
        var count = 0;
        while(true)
        {
            Console.Write("->");
            userWord = Console.ReadLine();
            if(userWord == "!") break;
            if(isValid(userWord, letters)) count++;
        }
        Console.WriteLine(count);
    }
    static bool isValid(string str, Dictionary<char, int> baseString)
    {
        return Regex.IsMatch(str, @"[а-яё]") &&
            str.GroupBy(c => c).ToDictionary(c => c.Key, c => c.Count())
            .All(x => baseString.ContainsKey(x.Key) && baseString[x.Key] >= x.Value);
    }
}

if(userWord == "!") break;

if(userWord == " ") break;