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 ":".
The
oldest
trees
in
the
forest
are
over
400
years
old
.
The:O
oldest:O
trees:O
in:O
the:O
forest:O
are:O
over:O
400:O
years:O
old:O
.:O