With no explanation, label each line with "O", "event-disaster", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
Believers
in
this
doomsday
event
usually
refer
to
this
object
as
``
Nibiru
``
or
Planet
X
.
Believers:O
in:O
this:O
doomsday:O
event:O
usually:O
refer:O
to:O
this:O
object:O
as:O
``:O
Nibiru:event-disaster
``:O
or:O
Planet:event-disaster
X:event-disaster
.:O