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 ":".
By
the
end
of
its
first
year
,
1
million
passengers
had
passed
through
its
doors
.
By:O
the:O
end:O
of:O
its:O
first:O
year:O
,:O
1:O
million:O
passengers:O
had:O
passed:O
through:O
its:O
doors:O
.:O