public string usedLetters()
        {
            StringBuilder sb = new StringBuilder();

            for (char c = 'a'; c < 'z'; c++)
            {
                if (VneseniBukvi.Contains(c))
                {
                    sb.Append(c);
                }
                else
                {
                    sb.Append("_");
                }
                sb.Append(" ");
            }
            return(sb.ToString());
        }
 public void guessLetter(char letter)
 {
     if (VneseniBukvi.Contains(letter))
     {
         return;
     }
     else if (Word.Contains(letter))
     {
         WordLetters.Add(letter);
         wordMask();
     }
     else
     {
         numWrong++;
         VneseniBukvi.Add(letter);
         usedLetters();
     }
 }