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 ":".
stretch
of
the
river
required
ferries
.
stretch:O
of:O
the:O
river:O
required:O
ferries:O
.:O