public static void main(String[] args){
    List<Integer> l = new LinkedList<Integer>();
    for(int i=1, size = Integer.valueOf(args[0]); i <= size; i++, Collections.reverse(l)){
        if(i%2 == 0) l.add(0, i); else l.add(i);
        System.out.println(Arrays.toString(l.toArray()).replaceAll(", ", "-").replaceAll("[\\[,\\]]", ""));
    }
}