With no explanation, label each line with "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport", "building-hospital" or "building-hotel" preceded by ":".
Their
histories
unknown
to
the
other
passengers
,
they
marry
each
other
on
board
the
vessel
.
Their:O
histories:O
unknown:O
to:O
the:O
other:O
passengers:O
,:O
they:O
marry:O
each:O
other:O
on:O
board:O
the:O
vessel:O
.:O