import java.io.File;

class DirectoryList {

    public static void main(String[] args) {
        if(args.length == 0) {
            System.err.println("Usage: DirectoryList <repository_name>");
            return; 
        }

        String repositoryName = args[0];

        File directory = new File(repositoryName);

        if(!directory.exists()) {
            System.err.println("Repository not found.");
            return; 
        }

        System.out.println(directory.getName());
        listFiles(directory, "\t");
    }

    private static void listFiles(File directory, String space) {
        if(!directory.isDirectory() || directory.listFiles().length == 0) return;

        for(File file : directory.listFiles()) {
            System.out.println(space + file.getName());
            listFiles(file, space + '\t');
        }
    }
}