using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var dictionary = new List<string> { "aabcd", "abcde", "bcdef" };

        var lettersWithBlank = new List<char> { 'a', 'b', 'c', 'd', '#' };

        FindWordsWithBlank(lettersWithBlank, dictionary);

    }

​

    public static void FindWordsWithBlank(List<char> letters, List<string> dictionary)

    {

        foreach (var word in dictionary)

        {

            var allowedLetters = new List<char>(letters);

​

            foreach (var wordLetter in word)

            {

                if (allowedLetters.Contains(wordLetter))

                {

                    allowedLetters.Remove(wordLetter);

                    continue;

                }

            }

​

            if (allowedLetters.Count == 1)

            {

                Console.WriteLine(word);

            }

        }

    }

}