import java.io.*;
import java.util.LinkedList;

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new FileReader(args[0]));
        BufferedWriter writer = new BufferedWriter(new FileWriter(args[1]));

        while(reader.ready()){
            String[] words = reader.readLine().split(" ");
            LinkedList<String> wordstoWrite = new LinkedList<>();
            for (String word: words) {
                word = word.replaceAll("[^\\w]","");
                word= word.replaceAll("[0-9]","");
                if(word.toCharArray().length>6){
                    wordstoWrite.add(word);
                }
            }
            String toWrite = String.join(",",wordstoWrite);
            writer.write(toWrite);
            wordstoWrite.clear();
        }
        writer.close();
        reader.close();

    }
}