def bracket(arr):
s = len(arr)
if s <= 2:
return arr;
return [bracket(arr[:s / 2]), bracket(arr[s / 2:])]
print bracket([1, 2, 5, 4, 7, 3, 6])
ZGVmIGJyYWNrZXQoYXJyKToKICAgIHMgPSBsZW4oYXJyKQogICAgaWYgcyA8PSAyOgogICAgICAgIHJldHVybiBhcnI7CiAgICByZXR1cm4gW2JyYWNrZXQoYXJyWzpzIC8gMl0pLCBicmFja2V0KGFycltzIC8gMjpdKV0KcHJpbnQgYnJhY2tldChbMSwgMiwgNSwgNCwgNywgMywgNl0p