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

public class Main {

    static class LeveledFile {
        public LeveledFile(File file, int level) {
            this.file = file;
            this.level = level;
        }

        public int getLevel() {
            return level;
        }

        public File getFile() {
            return file;
        }

        private File file;
        private int level;
    }

    public static void main(String[] args) {
        int maxLevel = 3;

        LinkedList<LeveledFile> stack = new LinkedList<LeveledFile>();
        stack.addLast(new LeveledFile(new File("./"), 1));

        while(!stack.isEmpty()) {
            LeveledFile current = stack.removeLast();
            System.out.println(current.getFile());

            if(current.getLevel() < maxLevel && current.getFile().isDirectory())
                for(File child : current.getFile().listFiles())
                    stack.addLast(new LeveledFile(child, current.getLevel() + 1));
        }
    }
}