using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.RegularExpressions;

// IMPORT LIBRARY PACKAGES NEEDED BY YOUR PROGRAM

// SOME CLASSES WITHIN A PACKAGE MAY BE RESTRICTED

// DEFINE ANY CLASS AND METHOD NEEDED

// CLASS BEGINS, THIS CLASS IS REQUIRED

public class Program

{

    public static void Main(){

        char[] splitChars = new char[] { ' ', '\'' };

        Console.WriteLine("Enter text to evaluate :");

        var literatureText = Console.ReadLine();

        Console.WriteLine("Enter word to exclude separated by space :");

        List<String> wordsToExclude = Console.ReadLine().Split(' ').ToList();

        List<String> literatureTextArr = literatureText.Split(splitChars).ToList();

        var filter = retrieveMostFrequentlyUsedWords(literatureTextArr,wordsToExclude);

        Console.WriteLine(string.Join(",",filter));

    }

    // METHOD SIGNATURE BEGINS, THIS METHOD IS REQUIRED

    static List<String> retrieveMostFrequentlyUsedWords(List<String> literatureTextArr, 

                                                   List<String> wordsToExclude)

    {

        List<String> cleanFilter = literatureTextArr.Where(x => wordsToExclude.Contains(x)).ToList();

        literatureTextArr.RemoveAll(x => cleanFilter.Contains(x));

        var duplicates = literatureTextArr

           .GroupBy(p => p)

           .Where(g => g.Count() > 1)

           .Select(g => g.Key).ToList();

        return duplicates;

    }

    // METHOD SIGNATURE ENDS

}