-module(dragon).
-export([start/0,dragon/1,dragon/2]).

dragon(N,D) when N == 1 -> io:fwrite("~w",[D]);
dragon(N,D) when N > 1 ->
    dragon(N-1,1),
    dragon(1,D),
    dragon(N-1,0).
dragon(N) -> dragon(N,1).

start()->
    dragon(12),
    io:fwrite("~n").